mi|e  ^(H^P  'piihtarits 

^0rtJ|  Carolina  ^tatc 


®l|is  boob  foas  presettteb  b^ 

Elizabeth  Stone 


THIS  BOOK  MUST  NOT  BE  TAKEN 
FROM  THE  LIBRARY  BUILDING. 


STRANGEWAYS' 

Veterinary  Anatomy 


TWELFTH  AMERICAN  EDITION 


REVISED   AND   EDITED 

BY 

I.  VAUGHAN,  F.L.S.,  FZ.S. 

KELIiOW  OF,  AND  EXAMINER   ON  OOMPARATIVE  ANATOMY  TO,  THE   ROYAL  COLLEGE  OF 

VETERINARY  SURGEONS,   I.ATE  LECTURER  ON  ANATOMY  AND  ZOOLOGY 

AT  THE  NEW  VETERINARY  COLLEGE,   EDINBURGH 


New  York 
WILLIAM  K.  JENKINS  CO. 

PUBLISHERS 

851-853  Sixth  Avenue 

1908 


TABLE   OF  CONTENTS. 


INTRODUCTION. 


ANATOMY, 

Vertebrata, . 
Domesticated  Mammals, 
Domesticated  Aves, 
Descriptive  Anatomy, 


FA«B 

1 

3 

4 
5 
6 


CHAPTER  I. 


OSTEOLOGY, 

Structure  of  bone,  . 
Osseous  tissue, 
Classes  of  bones, 

The  Skeleton,  . 
Axial  Skeleton, 
Vertebrffi,     . 
The  Ribs,     . 
Tbe  Sternum, 
General  view  of  the  Skull, 
Cranial  bones, 
Pacial  bones, 

Appendicttlar  Skeleton, 
Pectoral  arch  and  limb, 

Pelvic  arcli, 
Pelvic  limb, 

Comparative  Osteology, 
Ruminantia, 
Oranivora,  . 
Camivora,  .  , 

Rodentia,    .  , 

Aves, 


7 
7 
9 
12 

17 

21 
21 
33 
35 
37 
45 
54 

65 
66 

83 


105 
109 
114 
115 


TABLE    OF   CONTENTS. 


CHAPTER  IL 


ARTHEOLOGY, 

General  Anatomy,  . 
Classes  of  joints, 
Motion  in  joints;     . 

Articulations  of  the  Axial  Skeleton, 
Vertebral  articulations, 
Articulations  of  the  Skull, 


Articulations  of  the  Appendicular  Skeleton, 
Pectoral  limb, 
Pelvis  and  pelvic  limb, 


Comparative  Arthrologt, 


CHAPTER  III 


MYOLOGY, 

Muscular  tissue, 

Tendons, 

Fascia, 

Muscular  nomenclature, 

Classification  of  muscles. 

Subcutaneous  region, 

Tbe  Head,  . 

The  Trunk, 

Pectoral  limb, 

Pelvic  limb. 

Arrangement  of  the  fasciae. 

Table  of  muscular  attachments, 


Comparative  Myology, 


SPLANCHNOLOGY,      . 
Epithelium, 
Mucous  membranes, 
Serous  membranes. 
Glands, 

Digestive  System, 

Alimentary  canal,  . 

Mouth,         .     _ 

Palate, 

Tongue, 

Salivary  glands, 

Teeth, 


CHAPTER  IV, 


TABLE    OF   CONTENTS. 


Digestive  System — continued. 
Pharynx, 
CEsophagus, 
Abdomen,    . 
Stomach,     . 
Intestines,    . 
Accessory  organs  of  digestion 
Liver, 
Pancreas, 
Spleen, 
Peritoneum, 


Kespiratort  System, 
Nostrils, 
Kasal  chambers, 
Larynx, 
Trachea, 
Thyroid  and  Thymus  glands, 
Bronchi, 
Thorax, 
Pleurae, 
Lungs, 

Urinary  System, 
Kidneys, 
Ureters, 
Bladder, 

Generative  System, 
Male  Organs,  . 
Scrotum,      . 
Spermatic  cord, 
Testicle,      . 
Vas  deferens, 
Prostate  gland, 
Cowper's  glands, 
Urethra, 
Penis, 

Seminal  fluid, 
Female  Organs, 
Ovary, 

Fallopian  tubes. 
Uterus, 
Vagina, 
Vulva, 

Ma.mnnfl.ry  glands, 

Comparative  SPLAHcHNOLoaY, 


296 
298 
300 
301 
304 
312 
312 
318 
319 
321 


325 
327 
334 
335 
335 
336 
337 
337 

340 
340 
343 

344 

345 
346 
347 
347 
348 
350 
351 
352 
352 
353 
356 
357 
357 
368 
359 
361 
361 


TABLE   OF  CONTENTS. 


CHAPTER  y. 


ANGIOLOGY,      , 

Blood- Vasculab  System — Blood. 
Heart, 

Pericardium. 
Course  of  circulation, 

Arteries. 

Capillaries,  . 

Pulmonary  artery,  . 

Common  aorta. 

Posterior  aorta, 

Internal  iliac. 

External  iliac. 

Anterior  aorta, 

Brachial  artery. 

Cephalic  and  Carotid  arteries, 

Veins,     .  .  .  - 

Pulmonary  and  Systemic, 
Posterior  cava, 
Portal  vein. 
Iliac  veins,  . 
Anterior  cava. 
Brachial  vein, 
Jugular  vein. 

Lymphatic  System — Vessels, 

Glands, 

Lymph  and  Chyle,  . 

Thoracic  duct. 

Lymphatics  of  posterior  region, 
abdominal  viscera, 
thoracic  viscera, 
thoracic  walls, 
anterior  region, 

Lymphatic  vein, 

Comparative  Anqiology, 


VARV 

387 
387 
388 
397 
397 


400 
400 
401 
402 
409 
411 
418 
418 
424 

433 
435 
436 
437 

438 

442 
444 
446 


450 
451 
451 
452 
454 
455 
456 
456 
458 

458 


CHAPTER    VI. 


NEUROLOGY,     . 

Nervous  tissue, 
Nerves, 


465 
466 

467 


TABLE    OF    CONTENTS. 


XXI 


PAOB 

Cerebro-Spinal  System— Meninges, 

.      468 

Spinal  cord, 

.      471 

Brain, 

.      473 

Encephalic  circulation, 

.      485 

Cranial  nerves. 

490 

Spinal  nerves, 

.      502 

Brachial  plexus, 

.       508 

Lumbo-sacral  plexus, 

.            .            .            .511 

Sympathetic  System— Cephalic  portio 

n,          .            .            .            .515 

Cervical  portion,     . 

.       516 

Thoracic  portion,    . 

.       519 

Lumbar  portion,     . 

•       521 

Sacral  portion, 

.       521 

Comparative  Neurology, 


522 


CHAPTER  Vn. 


625 


STMJiiSlUljUlii, 

ORGANS  OF  SPECIAL  SENSE. 

The  Ear— External  ear,           ....           . 

525 

Middle  ear. 

....•• 

62(). 

Internal  ear, 

.       529' 

The  Eye— Tunics, 

. 

53a 

Humours,    . 

536 

Muscles, 

. 

.       537 

Appendages, 

ORGANS  OF  SENSATION. 

538 

The  Skin  and  its 

Appendages— Skin, 

.       541 

Hair, 

.       543 

Foot— Hoof, 

.       544 

Soft  parts  of  the  foot, 

.       54» 

Comparative  uEsthesiology,             .... 

.       552 

CHAPTER  VIIL 


lYOLOGY,. 

.      555 

Ovum  after  Fecundation,  . 

.       556 

Placenta, 

.      557 

Umbilical  cord. 

558 

Fcetal  circulation,  . 

.       559 

Development  of  Foetus,      . 

561 

^Xll  TABLE  OF  CONTENTS. 

APPENDIX. 

PAGE 

I,  General  directions  for  dissection,     .....  565 

II.  On  a  supernumerary  oblique  muscle  of  the  eyeball,            ,            ,  575 

III.  On  a  muscle  connected  with  the  orbital  periosteum,           •  577 

INDEX,    .•.,..,*.  583 


TABLE  OF  ILLUSTMTIONS. 


Tlate     I.  Skeleton  of  Horse,      . 

II.  Muscles  of  Horse— superficial  layer, 
III.  Muscles  of  Horse— deep  layer, 
17.  Digestive  and  Urinary  Organs  of  Horse, 
V.  Heart  and  cHef  blood-vessels  of  Horse, 
VI.  Nervous  System  of  Hors.e, 


PAO« 

.  opposite  page 

21 

161 

. 

193 

. 

274 

. 

400 

. 

503 

10. 

11. 

12. 
13. 
14. 
15. 
16. 
17. 
18. 
19. 
20. 
21. 
22. 
23. 


Transverse  sections  through  the  body  of  a  vertebrate 

brate  animal — diagramatic, 
Transverse  section  of  bone,     . 
Longitudinal  section  of  bone, 
Lacunae  of  bone. 
Section  of  ossifying  cartilage, 
Skeleton  of  Horse, 
Transverse  vertebral  segment, 
Cervical  vertebrae  articulated, 
Cervical  vertebra 
Skull  seen  from  above, 
Inferior  aspect  of  skull. 
Lateral  view  of  the  skull, 
Longitudinal  section  of  the  skull, 
Inferior  maxilla. 
Bones  of  the  hyoid  series, 
Bones  of  the  carpus,    . 
Bones  of  the  carpus,  metacarpus,  and  digit, 
Development  of  foot,  . 
Phalanges  disarticulated, 
Lateral  aspect  of  pelvis. 
Posterior  aspect  of  femur, 
Bones  of  tarsus. 
Bones  of  tarsus,  metatarsus,  and  digit, 


and  an 


inverte- 


10 
10 
16 

18 
22 
24 
25 
37 
39 
41 
43 
62 
64 
72 
73 
77 
79 
85 
89 
94 


TABLE   OF  ILLUSTRATIONS. 


FIG. 

24.  Posterior  aspect  of  metatarsu?, 

25.  Skeleton  of  Ox, 

26.  SkuUofOx,     . 

27.  Cardiac  bone  of  Ox,     . 

28.  Skull  of  Boar, 

29.  Skeleton  of  Hog, 

30.  Section  of  Hog's  skull, 

31.  Skeleton  of  Dog, 

32.  Bones  of  Digits  compared, 

33.  Clavicle  of  Dog, 

34.  Clavicle  of  Cat, 

35.  Os  penis  of  Dog, 

36.  Skeleton  of  Bird, 

37.  Sternum  of  Bird, 

38.  Skull  of  Fowl, 

39.  Pectoral  arch  of  Bird, 

40.  Pelvis  of  Bird, 

41.  Hyaline  cartilage, 

42.  White  fibrous  tissue,   . 

43.  Yellow  elastic  tissue,  . 

44.  Adipose  tissue, 

45.  Diarthrodial  joint — diagram 
40.  Odontoid  and  superior  cor- m on  ligaments, 

47.  Costo-vertebral  articulation — lateral  aspect, 

48.  Costo-vertebral  articulation — superior  aspect, 

49.  Temporo-maxillary  articulation, 

50.  Hyoid  articulations,     . 

51.  Ligaments  of  elbow  joint, 

52.  Ligaments  of  carpus — anterior, 

53.  Deep  ligaments  of  carpus — external 

54.  Deep  ligaments  of  carpus— postero-intemal, 

55.  Superficial  ligaments  of  carpus — posterior, 

56.  Sesamoidean  and  distal  ligaments,     , 

57.  Deep  sesamoidean  ligaments, 

58.  Navicular  Mgaments,    . 

59.  Sacral  and  pelvic  ligaments,   . 

60.  Sacral  and  pelvic  ligaments— inferior  view, 

61.  Ligaments  of  hip  joint, 

62.  Ligaments  of  stifle  joint, 

63.  Ligaments  of  stifle  joint — posterior  view, 

64.  Ligaments  of  tarsus — postero-intemal  view, 

65.  Ligaments  of  tarsus — antero-extemal  view, 

66.  Striated  muscular  fibres  and  tendon,  . 

67.  Musciilar  fibrillae, 

68.  Striated  muscular  fibres, 

69.  Non-striated  muscular  fibres,  . 


TABLE   OF   ILLUSTRATIONS. 


MG. 

PAOB 

70.  Muscles  of  head— lateral  view,          .           .           .            • 

165 

7  L  Muscles  of  maxillary  space. 

1 

171 

72.  Muscles  of  external  ear, 

175 

73.  Lateral  cervical  muscles, 

185 

74.  Occipito-atlo-axoid  muscles, 

188 

75.  Pectoral  muscles, 

195 

76.  Sublumbar  aud  internal  femoral  muscles,    . 

206 

77.  Diaphragm,    .            .            »            .            . 

•     209 

78.  External  muscles  of  anterior  limb,    , 

213 

79.  Internal  muscles  of  anterior  limb,    , 

216 

80.  Deep  muscles  of  arm, 

223 

81.  Flexor  muscles  of  fore-foot,    . 

227 

'82,  Section  of  digit. 

229 

83.  Deep  muscles  of  liip. 

233 

84.  Muscles  of  tliigb  and  haunch, 

240 

85.  Anterior  tibial  muscles, 

246 

86.  Posterior  tibial  muscles. 

250 

87.  Teudons  and  ligaments  of  Ox's  extremity, 

262 

88.  Epithelial  cells, 

.       270 

89.  Ciliated  epithelium. 

271 

90.  Muscles  of  tongue,  palate,  and  pharynx, 

.       279 

SI.  Parotid  and  molar  glands,     . 

.       285 

92.  Mouth  and  salivary  glands,  . 

286 

93.  Dentine,          .... 

.       289 

94.  Enamel,          .... 

.       290 

95.  Incisor  and  canine  teeth. 

.       292 

96.  Structai-e  of  incisor  tooth,     . 

.       292 

97.  Structure  of  molar  tooth, 

.       294 

98.  Stomach,        .... 

.       301 

99.  Internal  aspect  of  stomach,  . 

.       303 

100.  The  mesenteries, 

.       305 

101.  Section  of  mucous  membrane  of  intestine. 

1 

.       306 

102.  Chyle  magnided, 

.       307 

103.  Cajcum  and  great  colon, 

.       309 

104.  Liver  and  diaphragm. 

.       313 

105.  Hepatic  lobules  magnified,    . 

.       316 

lOG.  liUiary  and  pancreatic  ducts, 

.       317 

107.  Pancreas,        .... 

.      318 

108.  Spleen,            .... 

.       319 

109.  Relations  of  abdominal  viscera, 

.       320 

110.  Framework  of  nostril, 

.       324 

1 11.  Longitudinal  section  of  head, 

.       326 

112.  Epiglottis,      .... 

.       329 

1 13.  Ligaments  of  larynx — posterior  view, 

.       330 

114.  Ligaments  of  larynx— anterior  view, 

.       330 

1 15.  Muscles  of  larynx — lateral  view, 

.       332 

XXVI 


TABLE    OF   ILLUSTRATIONS. 


FIG. 

116.  Deep  muscles  of  larynx — lateral  view 

117.  Larynx  laid  open, 

118.  Respiratory  organs,    . 

119.  Capillaries  of  lung,    . 

120.  Section  of  kidney,      . 

121.  Structure  of  kidney, 

122.  Distribution  of  renal  artery, 

123.  Male  generative  organs, 

124.  Testicle, 

125.  Diagram  of  structure  of  testicle, 

126.  Bladder  and  urethra, 

127.  Female  urino-genital  organs, 

128.  Female  generative  organs,     . 

129.  Stomach  of  Ox, 

130.  Stomach  of  Sheep,      . 

131.  Rimiiiiaut  stomach  opened,  . 

132.  Stomach  of  Musk  Deer, 

133.  Mesentery  and  intestines  of  Ox, 

134.  Caecimi  of  Ox, 

135.  Liver  of  Ox, 

136.  Kidney  of  Ox, 

137.  Section  through  vagina  and  bladder  of  Co-vv, 

138.  Teeth  of  Hog, 

139.  Stomach  of  Hog, 

140.  Caecum  and  colon  of  Hog,     , 

141.  Liver  of  Hog, 

142.  Kidney  of  Hog, 

143.  Teeth  of  Caruivora,  . 

144.  Stomach  of  Dog, 

145.  Cpecum  and  colon  of  Dog, 

146.  Stomach,  liver,  &c.,  of  Dog,  . 

147.  Teeth  of  Rodent, 

148.  Alimentary  canal  of  Bird,     . 

149.  Urino-genital  organs  of  Bird, 

150.  Right  side  of  heart — opened, 

151.  Left  side  of  heart — opened,    . 

152.  Muscular  fibres  from  heart,  . 

153.  Diagram  of  circulation, 

154.  Heart  and  large  vessels  in  situ, 

155.  Abdominal  branches  of  posterior  aorta, 

156.  Arteries  of  crecum  and  colon, 

157.  Breaking  up  of  posterior  aorta, 

158.  Distribution  of  internal  iliacs, 

159.  Arteries  of  thigh,       .   - 

160.  Arteries  of  leg, 

161.  Arteries  of  neck. 


TABLE    OF   ILLUSTRATIONS. 


Fto. 

162.  Arteries  of  fore-limb, 

163.  Arteries  of  head, 

164.  Facial  arteries, 

165.  Posterior  vena  cava,  . 

166.  Portal  system, 

167.  Heart  and  great  veins, 

168.  Ve  ins  of  face  and  neck, 

169.  Section  of  lymphatic  gland, 

170.  Lympbathic  trunks,  . 

17 1.  Circulation  in  Reptile, 

1 72.  Circulation  in  Fish,  . 

173.  Circulation  in  Crustacean, 

174.  Nerve  tissue, 
1V5,  Pacinian  body, 

176.  Section  of  spinal  cord, 

177.  Base  of  brain, 

l'?8.  Brain  viewed  from  above, 

179.  Lateral  ventricles, 

180.  Cavities  of  brain — diagramatic, 

181.  Brain  laid  open, 

182.  Diagramatic  section  of  brain, 

183.  Encephalic  arteries, 

184.  Arteries  at  base  of  brain, 

185.  Origins  of  cranial  nerves, 

186.  Nerves  of  eye, 

187.  Fifth  nerve, 

188.  Facial  nerves, 

189.  Posterior  nerves  of  head, 

190.  Brachial  plexus, 

191.  Carpal  and  metacarpal  nerve, 

192.  Lumbo-sacral  plexus, 

193.  Tarsal  and  metatarsal  nerves, 

194.  Sympathetic  ganglion, 

195.  Nerves  of  thorax, 

196.  Abdominal  nerves,     . 

197.  Conchal  and  annular  cartilages, 

198.  Scutiform  cartilage,    . 

199.  Malleus, 

200.  Incus, 

201.  Stapes, 

202.  Tjpipanum,    . 

203.  Diagram  of  ear, 

204.  Membranous  labyrinth, 

205.  Diagram  of  eye, 

206.  Globe  of  eye, 

207.  Globe  of  eye — partly  opened, 


PAOE 

421 
428 
429 
436 
438 
443 
448 
450 
452 
463 
464 
464 
466 
467 
472 
474 
477 
481 
483 
484 
485 
486 
487 
491 
493 
495 
497 
501 
509 
510 
513 
514 
515 
517 
519 
526' 
526 
527 
527 
527 
528 
529 
531 


533 


TABLE    OF   ILLUSTRATIONS. 


FIG. 

PAOK 

208.  Pigment  cells, 534 

209.  Iris,     . 

635 

210,  Globe  of  eye— opened, 

536 

211.  Hoof,. 

546 

212.  Solar  aspect  of  hoof,  . 

547 

213.  Section  of  hom-tissue. 

. 

548 

214.  Sensitive  foot — solar  aspect, . 

55a 

215.  Sensitive  wall. 

551 

216.  FcEtus  of  Cow, 

558 

217.  FcEtus  of  Bitch, 

559 

218,  Foetal  circulation. 

.       560 

INTRODUCTION. 

Biology,  the  comprehensive  science  which  treats  of  living  or 
organised  bodies,  is  divisible  into  two  parts,  the  one  dealing  with 
the  Vegetable,  the  other  with  the  Animal  Kingdom.  Animal 
Anatomy,  or  Zootomy,  has  for  its  object  the  investigation  of  the 
animal  frame,  an  investigation  conducted  by  mechanically  divid- 
ing it  into  its  component  parts,  and  studying  their  form,  struc- 
ture, attachments,  and  relations.  Anatomy  may  be  Compai-ative, 
Special,  or  Transcendental,  according  to  the  scope  and  ultimate 
object  in  view.  Thus,  if  more  than  one  species  of  animal  be 
under  consideration,  the'  comparative  anatomist  takes  note  of 
their  various  deviations  and  similarities  ;  but,  if  the  investiga- 
tions be  confined  to  one  variety  of  animal,  as  in  Human 
Anatomy,  the  subject  then  becomes  special.  When  Special 
Anatomy  leads  to  the  thorough  investigation  of  one  single 
variety,  for  the  purpose  of  comparing  other  classes  with  it,  the 
subject  of  such  special  study  is  termed  a  type. 

Comparative  Anatomy,  therefore,  is  not  studied  hy  the  indis- 
criminate comparison  of  one  class  with  another,  but  by  referring 
them  to  certain  types  or  standards.  Embracing  as  it '  does  the 
structural  investigation  of  the  whole  animal  kingdom,  Compara- 
tive Anatomy  is  closely  related  to  the  science  of  Zoology,  the 
latter  science  aiming  especially  at  the  attainment  of  a  scientific 
method  of  classification.  Transcendental  or  Philosophical  Ana- 
tomy seeks  for  analogies  and  developmental  facts,  which  may 
guide  the  investigator  in  his  search  after  primary  anatomical 
types.  Since  the  prosecution  of  such  a  study  must  assume  a 
more  or  less  profound  knowledge  of  Comparative  Anatomy,  this 


2  INTRODUCTION. 

abstruse  branch  of  the  science  is  merely  alluded  to  here  in, 
passing. 

If  we  consider  a  portion  of  the  animal  body  with  respect  to 
its  form,  size,  relative  position,  or  structure,  we  are  said  to 
consider  it  anatomically  ;  but  should  we  inquire  into  the  use  or 
function  of  such  portion,  or  seek  to  know  the  changes  undergone 
by  it  while  in  a  living  condition,  then  we  are  investigating  it 
l^hysiologically.  Such  is  a  general  distinction  between  the 
sciences  of  Anatomy  and  Physiology ;  but  it  will  readily  be  seen 
that  they  are  to  a  great  extent  bound  up  in  one  another,  since 
both  the  sciences  must  lend  their  aid  to  afford  a  complete 
description  of  any  given  organ  or  part.  The  branch  treating 
solely  of  structure  and  form  is  termed  Morphology.  Histology, 
otherwise  called  General  or  Minute  Anatomy,  treats  of  the  intimate 
structure  of  the  tissues  or  materials  of  which  the  various  parts  of 
the  body  are  composed.  As  the  tissues  present  certain  character- 
istics invisible  to  the  naked  eye,  the  microscope  is  largely  employed 
by  the  histologist  in  his  investigations.  Embryology,  from  an 
anatomical  point  of  view,  is  a  science  considering  the  various 
appearances  presented  by  an  animal  after  each  of  the  many 
successive  stages  of  its  development, — from  when  it  first  appears 
as  a  mere  speck  of  vitality  until  it  has  acquired  the  general 
characteristics  of  a  perfect  animal. 

Anatomy,  in  all  the  above-mentioned  branches,  deals  only  with 
normal  or  healthy  material ;  but  should  such  material  be  in  a 
diseased  condition,  the  consideration  of  the  changes  it  has  conse- 
quently undergone  is  termed  Morbid  Anatomy.  Surgical  Anatomy 
embraces  the  description  and  investigation  of  such  parts  of  the 
body  as  are  most  liable  to  be  involved  in  surgical  operations. 
The  surgeon,  by  a  competent  knowledge  of  this  branch  of  the 
subject,  is  enabled  to  operate  with  the  maximum  of  safety  and 
expedition,  together  with  the  minimum  of  pain  and  inconvenience 
to  the  patient. 

Anatomy  in  either  of  its  aspects  may  be  descriptive  or 
practical.  In  the  former,  the  student  relies  on  books,  diagrams, 
lectures,  &c.,  for  his  information  ;  in  the  latter,  he  verifies  descrip- 
tions by  actual  dissection  and  demonstration  of  the  various 
structures  in  question. 

Veterinary  Anatomy,  in  the  full  sense  of  the  word,  includes  the 
anatomy  of  all  the  domesticated  animals,  and  is,  therefore,  a 
branch    of   the    comparative    science,   and    the    animal    usually 


INTRODUCTION.  3 

referred  to  as  its  type  is  the  Horse,  the  Anatomy  of  which 
animal,  or  Hippotomy,  is  primarily  considered  in  this  WorK, 
while  the  deviations  from  the  type,  which  make  up  the  compara- 
tive branch  of  the  subject,  will  be  noted  in  their  more  important 
features,  as  fully  as  the  scope  of  the  work  will  permit. 


VEllTEBRATA. 

As  all  the  domesticated  animals  belong  to  the  sub-kingdom 
Vertebrata,  it  is  of  importance  to  gain  a  clear  idea  of  the  lead- 
ing characteristics  of  a  vertebrate  animal ; 
and,  except  in  one  or  two  of  the  lowest 
orders,  these  are  well  marked. 

The  animal  kingdom  is  divided  into  the  /,. 
sub-kingdoms  Invertebrata  and  Verte- 
brata. As  the  names  would  imply,  the  latter 
is  distinguished  from  the  former  by  its 
members  possessing  a  vertebral  column, 
or  backbone,  which  forms,  as  it  were, 
the  axis  of  the  bony  framework,  supports 
the  head,  and  is  placed  dorsally,  or  in  the 
region  of  the  back,  extending  from  one  end  -^ 
of  the  body  to  the  other.  It  is  pierced 
throughout  the  greater  part  of  its  extent 
by  a  canal  called  the  neural  canal,  which 
is    continuous    with    a  cavity  in    the,  head  ^^°-*- 

,,     ,     ^,  ,  ~,  ...  A,    Diagramatic     transverse 

.called   the    cramum.       ihese  cavities   are  section  through  the  body  of  a 
occupied    by    centres,    from    which    radiate  vertebrate    b  a  simUar  sec- 

^  •'       .  '  tion  through  a  highly-organised 

the    large    series    of    nerves     termed     the  invertebrate  animal. 
cerehro-s-pinal    system.       Uoderneath    the  ,p";aT'n"1e'?cTntrL^;  ?no[o. 
backbone  there  is  a  second  series  of  nerve-  chord;  a,  sympathetic  nerve- 

,7     ..  ,  centres;  €,  Alimentary  canal; 

centres — those  oi  the  sympathetic  system.  /,  visceral  canaiwaii;g,Hffimai 
Thus    in    a    vertebrate    animal    there    are  system.-^/ier  NicnoLsoN. 
tiuo  systems  of  nerves,  whose  centres  are  separated  by  a  partition 
of  bone. 

The  remaining  portion  of  the  animal  body  may  be  regarded  as 
a  second  cavity,  or  canal,  which  contains,  in  addition  to  the 
sympathetic  system  of  nerves,  the  alimentary  and  the  kcemal 
systems.  The  former  runs  the  whole  length  _of  ±he  "body,  being 
a  canal  which  gives  passage  to  the  food ;   the  latter  consists  of 


4  INTRODUCTION. 

a  series  of  tubes,  by  which   the   blood   passes   through   the   body, 

both  systems  being  supplied  with  many  accessory  organs. 

In  the  higher  invertebrate  animal  we  find  no  backbone,  no 
neural  canal,  and  no  cerebro-spinal  system  of  nerves  ;  but  t'  e 
visceral  canal  exists,  and  its  contents  correspond  mostly  with  the 
structures  found  in  the  vertebrate.  (See  Fig.  1.)  The  lowest 
vertebrate  animals  known — the  Lancelot,  or  A'>niohioxus,  and  the 
Lamprey — have  no  vertebral  column,  but  they  possess  throughout 
Hfe  a  soft,  gelatinous  structure,  the  notochord,  from  which,  in  the 
higher  vertebrates,  the  column  becomes  early  developed.  These 
may  be  regarded  as  exceptional  or  undeveloped  forms. 

If  we  eliminate  from  the  Vertebrata  all  the  classes  but  the  two 
highest — the  Mamimalta  and  Aves — we  shall  further  localise  our 
subject,  since  these  two  classes  contain  all  the  animals  which,  as 
a  rule,  engage  the  attention  of  the  veterinary  anatomist,  to  whom 
the  first  of  the  two  is  of  by  far  the  greater  importance. 
DOMESTICATED    MAMMALS. 

It  is  sufficient  to  state  that  the  Mammalia  are  .characterised 
by  the  females  being  provided  with  an  apparatus  which  supplies 
milk  for  the  nourishment  of  their  young  after  birth. 

The  horse,  ass,  ox.  sheep,  goat,  camel,  llama,  pig,  elephant,  dog, 
cat,  and  rabbit  are  the  mammalian  vertebrates,  usually  included 
in  the  term  "domesticated  animals."  The  first  eight  of  these 
belong  to  one  of  the  most  important  of  the  natural  orders,  the 
Ungulata,  or  hoofed  animals.  The  camel,  llama,  and  elephant, 
not  being  domesticated,  in  the  proper  sense  of  the  word,  in 
Europe,  the  scope  of  the  present  work  will  not  permit  separate 
sections  to  be  devoted  to  their  description. 

UNGULATA. 

The  Ungulata  which  included  the  hoofed  quadrupeds,  is  a 
very  large  and  important  order,  divided  into  two  parts.  One 
section,  the  Perissod,acUjla,  includes  the  animals  having  an  odd 
number  of  toes  or  digits  ;  the  other,  the  ArtiodadyJa,  contain- 
ing those  with  an  even  number. 

PERISSODAOTYLX. 

Equidm  or  Solidungula. — The  horse  and  ass  are  referred,  in  the 
section  Perissodactyla.  to  this  family,  which  includes  only  the 
two  genera  Equus  and  Asinus  :  their  most  prominent  external 
feature  is  the  possession  of  only  one  perfect  digit  or  finger  on  each 
extremity.  Apparently  there  is  but  one  cleariy  defined  species  in 
the  genus  Equus,  the  features  presented  by  the  varieries  which  are 


INTRODUCTION,  5 

"known  as  "breeds"  being,  in  all  probability,  due  to  the  pro- 
longed influence  of  external  circumstances,  such  as  locality, 
.treatment,  climate  and  selection.  In  the  Equidse  the  stomach 
is  simple  and  comparatively  small. 

ARTIODACTYLA. 

Ruminantia. — The  ox,  sheep,  goat,  camel,  and  llama  belong 
to  this  section  of  ruminating  animals,  so  named  from  their  habit 
of  remasticating  their  food.  They,  are  all  cloven-footed,  or 
have  two  digits.  Very  generally  the  skull  of  the  ruminant  is 
provided  with  a  pair  of  horns ;  and  the  ox,  sheep,  and  goat  are 
classed  as  Cavicomia,  their  horns  being  hollow,  and  supported  on 
bony  cores.  Ruminants  are  mostly  without  front  teeth  in  the 
upper  jaw,  and  their  stomach  is  very  large  and  complex. 

Omnivora. — The  pig  is  classed  in  this  section.  Its  teeth  are 
of  a  mixed  order,  calculated  to  deal  with  many  kinds  of  food, 
hence  -the  name  Omnivora.  The  canine  or  eye  teeth  are  very 
prominent,  and  in  the  male  they  project  considerably  as  "  tusks," 
which  in  the  wilder  varieties  are  formidable  weapons.  The 
stomach  is  intermediate  in  complexity  between  that  of  the 
ruminant  and  that  of  the  horse.  This  animal  has  four  digits, 
two  long  and  two  short  on  each  extremity.  The  nose,  or  snout, 
is  prominent,  and  rather  cylindrical  in  form. 

CARNIVORA. 

Unlike  any  of  the  above-named  animals,  the  dog  and  cat  are 
placed  in  this  natural  order,  an  order  characterised  by  large 
canine  teeth,  and  by  there  being  no  lateral  or  grinding  motion 
between  tbe  jaws.  The  anterior  extremity  is  supplied  with  five, 
the  posterior  with  four  or  five  digits,  which  are  terminated  by 
sharp  or  blunt,  retractile  or  non-retractile  claws.  The  stomach 
is  small,  and  the  intestine  comparatively  short. 

RODENTIA. 

This  natural  order,  to  which  the  rabbit  belongs,  although  an 
extensive  order,  is  sufficiently  distinguished  by  the  possession  of 
two  large  chisel-shaped  incisor  or  front  teeth,  which  are  found  in 
each  jaw,  the  canine  teeth  being  altogether  wanting. 

DOMESTICATED  AVES. 
Birds   are   distinguished   from   Mammals   by  their   producing 
their  young  oviparously,  or  by  hatching  the  egg  outside  the  body. 


6  INTRODUCTION. 

They  never  suckle  their  young,  and  have  a  covering  of  feathers- 
Such  of  these  as  we  have  to  allude  to  belong  either  to  the  natural 
order  Rasores  or  to  the  Natatores.  the  former  including  the 
terrestrial  birds  and  pigeons,  the  latter  the  various  aquatic  species, 
distinguished  by  their  web  feet 

DESCRIPTIVE   ANATOMY. 

Osteology  is  a  term  applied  to  that  section  of  descriptive 
anatomy  which  treats  of  the  bones.  Arthrology  to  the  considera- 
tion of  the  joints  or  modes  of  union  between  the  bones,  while  by 
Myology  is  meant  the  doctrine  of  the  muscular  system.  Splanch- 
nology treats  of  the  viscera,  Angiology  of  the  circulatory  and 
absorbent  systems.  Neurology  deals  with  the  nervous  system. 
JEsthesiology  with  the  organs  of  sense  ;  while  Embryology,  as 
before  stated,  is  the  consideration  of  the  animal  frame  at  periods 
preceding  its  birth.  In  this  work  the  various  departments  are 
discussed  in  the  order  here  given.  The  structures  which  are  the 
subjects  of  the  first  three  divisions  are  sometimes  classed  together 
as  the  Organs  of  Locomotion,  for  bones  form  the  framework 
of  the  body  and  often  act  as  levers ;  the  joints  connect  the 
bones,  permitting  more  or  less  motion  between  them  ;  while  the 
muscles  move  the  bones,  and  so  produce  motion  of  a  part  of  the 
body — or  it  may  be  locomotion,  or  change  of  situation  in  the 
entire  frame. 

In  the  study  of  Comparative  Anatomy  the  terms  anaUjy  and 
homology  are  frequently  met  with.  Although  these  words  are 
not  unfrequently  used  indiscriminately,  the  following  difference 
should  be  noted.  Organs  are  said  to  be  analogous  when,  though 
differing  in  structure,  they  perform  the  same  function  ;  but  when 
their  functions  are  different,  while,  in  the  broad  sense,  they 
correspond  in  structure  or  form,  they  are  said  to  be  homologous. 
Thus  the  middle  finger  of  the  human  hand  is  the  homologue  of 
the  anterior  digit  of  a  horse,  because  they  have  the  same  general 
structure,  and  relation  to  the  rest  of  the  limb;  but  as  the 
functions  thf^y  perform  are  quite  dissimilar,  they  cannot  be 
termed  analogous.  Again,  the  lungs  of  a  mammal  are  analogous 
to  the  gills  of  a  fish,  for,  though  they  differ  widely  in  structure, 
position,  and  form,  and  are  therefore  not  homologous,  their 
ultimate  use  is  the  same — each  of  them  being  an  apparatus  in 
which  is  carried  on  the  process  of  purifying  the  blood. 


CHAPTER  I. 

OSTEOLOGY. 
STKUCTURE     OF    BONE. 

Bones  are  hard,  yellowisli- white,  insensitive  bodies,  wliich  form 
the  internal  or  e^icZoskeleton.  give  attachment  to  soft  structures, 
and  are  of  various  sizes,  forms,  and  densities.  In  the  limbs  the 
bones  are  usually  more  or  less  cylindrical,  with  expanded 
extremities,  and  not  only  effectually  support  the  body,  and 
afford  leverage  and  attachment  to  the  muscles,  but,  by  uniting,, 
form  the  articulations  or  joints.  Where  cavities,  such  as  the 
cranium,  chest  and  pelvis,  enclose  viscera  requiring  protection, 
and  support,  the  bones  tend  to  assume  a  flat,  expanded  form. 

Living  bone  is  bluish  pink,  insensitive,  and  elastic ;  on  ex- 
posure to  air  it  becomes  diseased,  assumes  a  black  or  livid  hue, 
and  is  extremely  sensitive  and  painful;  the  teeth  excepted,  it 
is  harder  and  of  a  higher  specific  gravity  than  any  other  animal 
tissue.  Consisting  as  it  does  of  inorganic  salts  deposited  in  a 
basis  of  animal  matter,  to  the  former  it  owes  its  density  and 
hardness,  to  the  latter,  its  elasticity  and  tenacity — the  union 
rendering  the  tissue  solid  and  elastic  enough  to  obviate  fracture 
from  ordinary  causes.  Its  components  are  so  intimately  blended 
that,  to  the  naked  eye,  it  appears  homogeneous,  but,  by  steeping 
in  dilute  hydrochloric,  or  other  strong  mineral  acid,  the  earthy 
matter  is  dissolved,  while  the  tough  flexile  animal  cast  is  left. 
Again,  if  we  expose  it  to  the  action  of  heat  we  get  rid  of  the 
animal  matter,  and  a  white,  brittle,  earthy,  chalky  substance  is 
left,  retaining  its  original  shape. 

The  relative  proportions  of  animal  and  earthy  matter  vary  at 
different  periods  of  life.  In  the  young,  the  organic  constitutes 
nearly  one-half  of  the  bone  ;  in  the  adult,  it  diminishes  to  about 
a  third,  while  in  old  animals  it  is  still  less  ;  hence  the  bones 
of  very    old    animals    are    brittle,    and    more  liable    to   fracture. 


8 


OSTEOLOGY. 


The  animal  and  earthy  proportions  do  not  vary  in  the  true  bone 
tissue,  but  there  is  a  gradual  filling  up  of  the  cavities  originally 
occupied  by  fat  cells,  thus  condensing  the  bone.  The  earthy 
ingredients  consist  chiefly  of  carbonate  and  phosphate  of  lime  ; 
the  animal  matter  of  cartilage  and  connective  tissue,  vessels, 
membranes  lining  the  cancellated  structure  and  medullary 
cavities,  and  a  quantity  of  fat.  The  following  is  an  average 
analvsis  of  osseous  tissue  by  Von  Bibra  : — 


Phosphate  of  T,ime,  with  trace  of\ 
Fluoride  Calcium,      .         .         .  J 
Carbonate  of  Lime, 
Phosphate  of  Magnesia, 
Soluble  Salts,         .    '     . 

Femur  ot 
old'sh^ep. 

Femur  of 

4-year 
old  BuU. 

Femur  of 

6-year 
old  Horse. 

Humerus 
of  6-year 
old  Cat. 

55-94 

12-18 
1-00 
0-50 

54-07 

12-71 
1-42 
0-80 

54-37 

12-00 
1-83 
0-70 

59-30 

10-69 
1-70 
0-40 

69-62 

69-00 

68-90 

72-09 

Cartilage, 

Fat,  &c., 

29-68 
0-70 

29-09 
1-91 

27-99 
3-11 

27-21 
0-70 

30-38 

31-00 

31-10 

27-91 

100-00 

100-00 

100-00 

100-00 

In  adult  bones,  as  above  stated,  the  proportion  of  animal 
-matter  is  about  a  third,  varying  in  different  animals,  and  in 
different  bones  of  the  same  animal.  The  bones  of  the  young  may 
have  too  great  a  proportion  of  animal  matter,  when  they  give  way 
under  the  superincumbent  weight,  as  in  rachitis,  when,  ossifica- 
tion advancing,  the  animal  becomes  a  cripple.  The  degree  of 
hardness  varies  not  only  with  the  age,  but  also  with  the  class  of 
the  animal,  the  bones  of  birds  being  white,  hard,  and  brittle, 
especially  those  of  the  wings  and  legs;  the  bones  of  the  chamois 
and  its  congeners  are  also  very  hard  and  brittle,  whereas  fish 
bones  are  soft  and  flexible.  The  bones  of  some  fishes  contain  a 
very  large  proportion  of  animal  matter,  and  these  are  known  as 
the  cartilaginous  fishes.  In  different  parts  of  the  same  skeleton 
they  vary  in  hardness,  the  petrosal  bone  being  the  hardest  one  in 
the  body ;  the  shank  bones  are  also  very  hard  and  dense,  while 
the  ribs  are  soft  and  flexible.  The  leg  bones  of  a  thorough- 
hved  horse  are  more  comwact  than  those  of  a  heavy  cart-horse ; 


OSSEOUS    TISSUE.  9 

the  latter  are  larger,  but  do  not  weigh  as  much  in  proportion^ 
because  the  shell,  or  outer  layer,  is  more  expanded  and  thinner, 
affordifflg  greater  surface  for  muscular  attachments.  Whereas, 
in  the  thorough-bred,  a  greater  density  of  bone  is  necessary  to 
withstand  the  intense  concussion  of  speedy  action  ;  therefore  the 
bones  are  increased  in  thickness  of  shell,  affording  greater  strength, 
without  apparent  increase  in  size. 

OSSEOUS   TISSUE. 

In  bone  tissue  there  are  two  modifications  of  texture,  the  com- 
pact and  the  cancellated.  The  former — hard,  dense,  and  ivory- 
like— is  always  situated  externally ;  the  latter — porous  and 
spongy — lies  within. 

Although     the    compact  -__^i1ii^>/i'-=^^^s:^- 

tissue  appears  uniformly 
dense,  and  destitute  of  por- 
osity, yet,  if  we  transversely 
sectate  the  shaft  of  a  long 
bone,  and  examine  it  under 
the  microscope,  by  trans- 
mitted light,  it  is  found  to 
contain  numerous  round 
openings.  These  are  called 
Haversian  canals.  They 
transmit  blood-vessels,  and 
run  in  a  longitudinal  or 
slightly    oblique    direction, 

opening  on  either  the  outer    the  peripheral  and  mterstitiallamellffi. 

or    inner     surface     of    the 

bone  ;  they  also  have   many  transverse  branches  of  communica- 
tion, which  are  often  of  greater  diameter  than  the  trunks.     These 
canals  are  from   ^th  to    iTrrffth    of^an    inch  in  diameter,  and 
surrounded  by  concentric  layers  or  lamellce  of  bone,  which  are 
shady  or  opaque,  and  vary  in  number  from  two  or  three  to  six,  the 
internal  being  most  distinct,  each  succeeding  one  becoming  less  so. 
Between  them  may  be  seen  many  dark,  irregulavly-oval  objects 
— the    minute  reservoirs   or  lacunce,  containing  the  hone-corpus- 
cles,   from    which    numerous    radiating    processes    occupy    the- 
canal icul i ;    the   latter    are    minute    canals,    which    establish  a. 
communication  between  the  Haversian  canals  and  the  lacun&.. 
On  the   external    part   of  the   shell  of  the   compact   tissue     of 
long  bones  are  several  concentric  osseous  layers,  the  peripheral 


Fig.  2. 
Transverse  section  of  compact  osseous  tissue.  An 
Haversian  canal,  3,  is  seen  surronnded  by  concentric 
layers,  forming  an  Haversian  cylinder,  1.  The  dark 
objects  between  the  lamella  are  lacunae  ;  2  is  a  similar 
cylinder,  showing  also  the  canalicuU  ;  4  4,  Portions  of 


10 


OSTEOLOGY. 


» 


Longitudinal  section  of  osseous 
tissue,  showing  the  arrangement  of 
the  Haversian  canals. 


or  periosteal  lamelliB,  passing  completely  rouud  the  shaft. 
There  is  also  a  corresponding  concentric  disposition  of 
layers  on  the  inner  or  medullary  surface. 
Both  these  systems  of  lamellae  are  in  a 
great  measure  destitute  of  Haversian 
canals,  and  are  supplied  with  nutritive 
material  by  means  of  lacunae  and  cana- 
liculi,  disposed  as  in  the  compact  tissue 
generally. 

The  average  diameter  of  the  canaliculi 
is  Tinr^th  of  an  inch.  The  lacunae  are 
somewhat  oval,  and  lie  with  their  long 
diameters,  which  measure  about  rs^th 
of  an  inch,  parallel  to  the  lamellae  ;  their 
short  diameter  is  about  TreVoth  of  an 
inch.  The  compact  tissue  is  therefore 
copiously  supplied  with  nutriment  by 
means  of  minute  vessels,  which  enter  from  almost  every  conceiv- 
able point.  Each  Haversian 
canal  may  be  considered  a  vas- 
cular longitudinal  centre,  round 
Y/hich  successive  concentric  layers 
of  bone  are  arranged,  so  as  to 
form  a  dense  cylindrical  ossicle, 
a  Haversian  System  or  Cylinder. 
Series  of  these  are  repeated, 
and  united  by  lamellae  destitute 
of  canal.s,  but  with  numerous 
canaliculi  and  lacunse,  and  called  the  connecting  or  interstitial 
lamellce,  the  entire  structure  being  encircled  by  the  external 
peripheral  lamellae,  thus  constituting  the  compact  tissue,  and 
in  such  a  way  as  to  combine  strength  and  density  with  efficient 
nutrition,  the  nutritive  material  being  conveyed  by  the  canals, 
canaliculi,  and  lacunae  ;  the  last  two  only  transmit  the  Jltiid 
portion  of  the  blood.  The  canaliculi  interlace,  and  some  pass 
directly  through  the  lamellae  to  the  central  Haversian  canal. 
The  lamellae  are  in  places  pierced,  and,  as  it  were,  pinned 
together  by  fibres,  or  fibrous  bundles  known  as  the  perforating 
fibres  of  Sharpey  ;  some  of  these  are  derived  from  the  perios- 
teum, and  some  even  appear  to  be  continued  from  inserted 
tendons  and  ligaments. 


Fig.  4. 
Lacuna;    highly   magnified 
lacuna  ;  h  b.  The  canaliculi ; 


a,    Cavity   of 
those  of  the  two 


lacunas  on  the  left  are  seen  to  join  each  other. 


COVEEING   OF   BONE.  11 

Cancellated  or  spongy  tissue  is  always  situated  internally.  It 
consists  of  a  large  number  of  fragile  bony  plates,  with  spaces 
between  them  called  the  cancelli  ;  there  are  lacunae  and  canali- 
culi,  but  no  Haversian  canals,  their  place  being  taken  by  the 
cancelli ;  in  the  bones  of  the  cranium  this  tissue  is  called  the 
diploe, 

COVEEING   OF  BONE. 

The  external  surface  of  every  bone  is  covered  by  a  tough, 
fibro-vascular,  inelastic  membrane,  the  periosteum,  excepting 
where  tendons  play  over  the  bone,  and  its  articular  surfaces 
upon  which  there  is  a  layer  of  cartilage.  The  periosteum, 
firmly  adherent  to  the  boue,  contains  minute  blood-vessels, 
which  are  thickly  distributed  before  entering  the  osseous  tissue, 
and  it  consists  of  two  layers — aa  outer  one,  fibrous  and  protect- 
ive, and  an  inner  one,  which  consists  of  fine  connective  tissue, 
contains  bone-producing  cells,  or  osteoblasts,  and  has  been  termed 
the  osteogenic  membrane.  The  inner  layer  is  continued  into 
the  Haversian  canals,  a  layer  of  cells  also  existing  between 
the  canal  wall  and  the  contained  vessel.  It  affords  support 
and  protection  to  the  bone,  and  attachment  to  tendons  and 
ligaments,  which  frequently  become  continuous  with  it.  It 
varies  in  thickness,  being  dense  and  strong  on  bones  nearest 
the  skin,  and  liable  to  injury ;  in  the  horse,  it  is  well  devel- 
oped on  the  inner  surface  of  the  tibia,  and  over  the  anterior 
surfaces  of  the  metacarpal  and  metatarsal  bones.  By  its 
strength  it  sometimes  retains  the  fragments  of  a  bone  in  con- 
tact after  an  oblique  fracture ;  in  the  young,  it  is  thicker  and 
more  vascular  than  in  the  adult.  Blood-vessels  which  ramify 
in  the  periosteum  pass  directly  to  the  bone  ;  the  external 
surface  of  a  bone  is  always  studded  with  numerous  foramina 
through  which  these  enter. 

The  periosteum,  owing  to  its  inelasticity,  is,  when  inflamed, 
the  seat  of  intense  pain  ;  and  should  any  part  of  it  be  stripped 
off,  there  is  every  probability  of  the  denuded  bone  dying  and 
exfoliating.  It  is  most  vascular  near  the  joints,  where  it  termi- 
nates by  joining  the  articular  cartilage,  or  passes  to  the  next 
bone,  but  it  never  covers  an  articular  surface.  The  internal  or 
medullary  cavities  are  lined  by  a  more  delicate  vascular  mem- 
brane, the  endosteum.  or  medullary  membrane,  which  is  pro- 
longed into  the  cancelli  and  Haversian  canals.  It  is  very  thin, 
consisting  of  delicate  areolar  tissue,  filaments  from  which  serve 
to  support  the  marrow,  the  nutrient  or  medullary  arteries,  enter- 


12  OSTEOLOGY. 

ing  the  bones  by  the  so-called  nutrient  foramina,  being  chiefly 
distributed  in  it.  The  periosteum  covering  the  bones  of  the 
cranial  vault  is  called  the  pericranium. 

CONTENTS   OF  BONES. 

Bones  contain  Marrow,  Connective  Tissue,  Blood-vessels, 
Lymphatics,  and  Nerves. 

Marroiv,  as  found  in  the  shafts  of  long  bones,  is  a  soft, 
yellowish  adipose  or  fatty  material,  which  is  contained  in  a 
delicate  layer  of  connective  tissue,  and  supported  by  inflective 
processes  of  the  same.  A  few  cells  are  found  in  yellow  mar- 
row. Cancellated  tissue  contains  what  is  termed  the  red 
marrow,  a  substance  consisting  for  the  most  part  of  marroiv- 
jells,  which  are  round  and  nucleated,  but  also  containing  some 
smaller  objects  resembling  embryonic  blood-corpuscles,  and 
some  very  large  cells.  These  latter  contain  numerous  nuclei, 
and  they  are  known  as  the  giant  cells,  otherwise  myeloplaxes. 

The  connective  tissue  lining  the  medullary  canal  and  cancelli 
forms  the  above-mentioned  endosteum.  The  large  bones  of  most 
birds  in  adult  life  contain  air  instead  of  marrow,  but  in  the 
bones  of  a  mammal  in  perfect  health  there  is  a  considerable 
quantity  of  the  latter,  which  becomes  diminished  in  disease. 

Blood-vessels  are  numerous  in  bone  tissue  ;  tlie  arteries  rami- 
fying in  the  periosteum  gain  the  Haversian  canals,  the  medul- 
lary artery  enters  by  the  nutrient  foramen,  and  the  arteries  of 
the  cancellated  tissue  pass  through  foramina  situated  near  the 
articular  surfaces.  The  veins  are  numerous,  and,  according  to 
recent  observation,  do  not  generally  accompany  the  arteries 
but  occupy  separate  canals;  tbe  diploe  in  the  cranial  bones 
contains  large  dilated  veins.  Lymphatics  exist,  but  little  more 
is  as  yet  known  of  them  than  that  lymph  spaces  are  found  in 
the  Haversian  canals.  Nerves  likewise  exist  in  osseous  tissue, 
in  its  coverings,  and  also  in  marrow — accompanying  the 
various  blood-vessels. 

CLASSES    OF   BONES. 

Bones  are  classed  as  long,  flat,  and  irregular.  Long  or 
cylindrical  bones  are  found  in  the  extremities,  where  they 
serve  as  levers,  and  pillars  of  support.  Descriptively,  a  long 
bone  is  divisible  into  a  centre  or  shaft  and  extremities.  The 
shaft  is  cylindrical,  and  consists  of  a  shell  of  compact  tissue  of 
varying  thickness,  which  encloses  the  cancellated  tissue  and 
medullary  canal,  and  is  pierced  by  the  medullary  or  nutrient 


CLASSES-  OF  BONES.  13 

foramen;  it  is  smallest  in  the  centre,  expanding  towards  the 
extremities,  and  is  circular,  oval,  or  prismoid  in  form.  "When 
a  long  bone  is  placed  nearly  vertically  uuder  the  body,  the 
internal  wall  of  its  shaft  is  usually  the  thickest.  When 
obliquely  placed,  the  thick  portions  of  the  shaft  correspond 
with  the  lines  which  would  indicate  the  direction  of  pressure 
produced  by  the  animal's  weight.  Long  bones  are  never 
straight ;  they  may  be  twisted,  as  is  the  humerus,  and,  if  bent, 
are  generally  convex  on  their  exbosed  surfaces,  the  shell  being 
thickest  on  the  concave  side. 

The  extremities  of  long  bones  always  exceed  the  shaft  in  cir- 
cumference, and  are  remarkable  for  the  irregularity  of  their  outline; 
they  are  expanded  and  roughened,  to  afford  surface  for  the 
attachment  of  tendons  and  ligaments,  .-their  protuberances  also 
materially  increasing  the  mechanical  power  of  muscles  by  serving 
as  pulleys  over  which  the  tendons  play.  The'  extremities  are 
composed  of  cancellated,  with  a  thin  layer  of  compact,  tissue,  the 
cancellated  getting  gradually  less  dense  towards  the  centre  of  the 
shaft,  which  is  occupied  by  the  medullary  canal.  While  the 
extremities  exceed  the  shaft  in  circumference,  their  weight  is 
not  relatively  greater — their  increase  being  due  to  a  diffusion  and 
expansion  of  material,  not  to  an  addition  of  substance.  This 
arrangement  hghtens  and  strengthens  the  bone,  besides  filling  its 
cavities  with  an  elastic  material  to  resist  concussion.  The 
hardest  part  of  a  bone  is  usually  the  thin  portion  lying  next  to 
the  articular  surface ;  it  is  only  found  when  the  bone  is  fully 
developed,  and  it  rests  upon  a  series  of  arches  formed  by  the 
cancelli :  this  thin  layer  is  covered  with  cartilage.  Excepting 
on  their  articulating  surfaces,  the  extremities  of  long  bones 
are  copiously  pierced  by  foramina,  which  chiefly  transmit 
blood-vessels  to  and  from  the  interior. 

Flat  or  tahalar  hones  afford  extensive  surface  for  muscular 
attachment,  and  help  to  enclose  cavities  containing  important 
organs.  Thus,  the  cranium  protects  the  brain,  the  scapula  and 
ribs  protect  the  respiratory  organs  and  heart.  Flat  bones  are 
composed  of  two  thin  expanded  plates  of  compact  tissue, 
rarely  quite  parallel  to  each  other,  and  enclosing  a  cancellated 
structure  between  them.  The  internal  is  considerably  harder 
than  the  external  plate,  but  not  so  thick  or  tough,  the  outer 
being  more  elastic  and  less  liable  to  fracture ;  the  connecting 
cancellated  tissue  is  plentifully  supplied  with  blood-vessels. 
In  the  bones  of  the  cranium,  the  compact  plates  are  called  the 


14  OSTEOLOGY. 

tables,  and  the  spongy  tissue  between,  the  diploe' ;  the  tables 
also  in  some  facial  bones  may  be  widely  separated,  with  air 
cavities  between  them. 

Irregular  hones  include  all  which  are  classed  with  the  fore- 
going. They  are  found  in  the  vertebral  column,  in  the  skull, 
and  also  in  the  limbs.  They  usually  possess  many  angles  and 
indentations,  with  surfaces  for  articulation  aud  tendinous 
attachment,  and  consist  of  a  thin,  dense,  external  case  of 
compact  bone  enclosing  cancellated  tissue.  In  proportion  to 
their  size  they  present  a  much  larger  extent  of  articular 
surface  and  greater  mechanical  strength  than  any  other  class. 

SURFACES   OF  BONES. 

No  bone  is  strictly  geometrical  in  form,  although,  to  a  casual 
observer,  some  may  appear  so.  The  chief  irregularities  consist  of 
certain  eminences  and  depressions,  a  knowledge  of  which  is  one 
of  the  first  requisites  in  the  study  of  osteology.  Eminences  and 
depressions  Qxe  articular  or  non-articular  ;  the  former  are  clothed 
with  cartilage,  and  assist  in  the  formation  of  joints. 

Non-articular  eminences  exist  extensively  on  the  external 
surfaces  of  most  bones,  and  receive  the  attachments  of  tendons 
and  ligaments.  They  are  of  various  shapes,  sizes,  and  densities, 
and  frequently  named  from  their  real  or  supposed  resemblance  to 
some  known  object. 

The  term  process  or  apophysis,  may  be  generally  applied  to 
prominent- elevations,  but  processes  so  called  are  not  necessarily 
non-articular,  and  certain  other  terms  are,  rather  arbitrarily, 
applied.  A  spine  is  an  elevation  which  tends  to  become  pointed  ; 
a  tubercle  is  a  small  blunt  projection,  which,  if  more  developed, 
would  be  called  a  tuberosity,  while  the  name  trochanter  is 
applied  to  the  largest  and  most  prominent  of  these  A  crest  or 
ridge  implies  a  roughened  line  or  border. 

Non-articular  depressions  may  serve  as  channels  of  trans- 
mission, passing  completely  through  a  bone  or  part  of  a  bone, 
and  may  bear  either  of  the  names  foramen,  canal,  aqueduct,  or 
w.eatus,  the  first  name  being  the  most  used  ;  or  they  may  be 
blind  cavities  in  the  surface  of  jhe  bone,  and  if  roughened  for 
the  attachment  of  tendons  or  ligaments,  the  term  fossa  is  some- 
times applied  to  them.  The  terms  notch  and  fissure  indicate 
depressions  or  grooves,  which  transmit  various  structures,  and  the 
approximation  of  two  notches  in  contiguous  bones  .  sometimes 
forms  a  foramen.  When  we  find  a  depression  leading  to  two  or 
more  foramina  it  may  be  termed  an  hiatus. 


DEVELOPMENT    OF   BONE.  15 

Articular  eminences. — A  caput  or  head  is  a  more  or  less  semi- 
spherical  projection,  supported  by  a  roughened  and  constricted 
cervix  or  neck.  An  ovoid  convexity  is  called  a  condyle;  and 
often  condyles  are  found  in  pairs,  the  articular  surfaces  of 
which  may  be  continuous  or  separated.  A  trochlea  is  an 
articular  surface  presenting  a  pulley-like  appearance. 

Articular  depressions. — A  glenoid  cavity  is  shallow,  and  may 

be  cup-like,  while  a  cavity  is  called  cotyloid  when  it  is  deeper. 

The  term  facet  is  often  applied  to  articular  surfaces,  which  may  be 

large,  but  are  not  well  marked  either  as  elevations  or  depressions. 
The  rough  irregularities  of  surface  are  more  distinctly  marked 

in  the  bones  of  the  horse  than  in   those  of  most  other  animals; 

their  size  is  always  proportionally  greater  in  well-bred  animals  ; 

in  heavy,  coarsely-bred  horses,  which   possess  great  strength  but 

little  activity,  they  are  smaller  in  proportion  to  the  absolute  size 

of  the  bones. 

DEVELOPMENT    OF    BONE. 

Although  the  bones  of  the  foal,  calf,  and  young  of  many  other 
large  quadrupeds,  possess  greater  solidity  at  birth  than  those  of 
the  human  infant,  yet  they  all  pass  through  certain  progressive 
stages  of  development  before  arriving  at  that  degree  of  density 
which  they  ultimately  possess.  The  tracing  of  future  bone  is 
recognised,  about  the  seventh  week  of  foetal  development,  in  local 
collections  of  soft,  granular,  gelatinous  pulp,  which  becomes 
gradually  flooded  with  nucleated  cells,  held  together  by  an  opaque, 
intercellular  basis  or  matrix,  which,  with  the  cells  equally  dis- 
tributed through  it,  forms  te'mporary  cartilage — a  material  closely 
resembling  in  its  properties  ordinary  gristle. 

The  process  of  ossification,  or  conversion  of  cartilage  into  bone, 
begins  at  certain  fixed  points,  and  gradually  spreads ;  these  points 
are  called  ossific  centres,  or  points  of  ossification.  When  this 
conversion  commences,  that  part  of  the  cartilage  about  to  become 
ossified  is  permeated  by  large  channels  for  the  passage  of  the 
blood-vessels  which  convey  the  bone-earth ;  and  the  cells,  instead 
of  being  equally  distributed  throughout  the  matrix,  become 
arranged  in  parallel  groups,  and  increase  in  number,  those  nearest 
the  point  of  ossification  enlarging.  Matter,  in  the  form  of  very 
minute  granules,  is  now  deposited  in  this  column  of  intercellular 
or  hyaline  substance,  as  well  as  between  each  cell. 

Ossification  of  the  cell  walls  ensues,  which  is  followed  by  the 
absorption  of  the  osseous  matter  between  the  cells,  converting 
what  was  a  row  of  closed  cells  into  a  tube,  which  is  a  rudiment- 


16  OSTEOLOGY. 

irj  Haversian  canal,  no  trace  being  left  of  the  nucleus  of  the 
original  cartilage  corpuscle ;  but  there  are  numerous  very  minute 
reddish  granules,  which  almost  fill  the  cavity,  and  are  concerned 
in  the  formation  of  blood-vessels,  which  now  begin  to  appear. 
The  ossific  parietes  of  the  cartilage  cells  lining  the  tube,  at  first 
thin,  enlarge  and  thicken  by  successive  layers  of  dense  osseous 
matter,  and  thus  produce  the  concentric  lamellae,  the  lamella  last 
formed  pushing  out  the  older  one,  until  what  was  the  lining  of 
the  tube  becomes  the  external  lamella  of  an  Haversian  system, 
while  the  ossific  matter  which  was  deposited  in  the  column  of 
intercellular  material,  becomes  the  connecting  lamellae  between 
the  Haversian  cylinders. 

In  long  bones  this  ossific  process  commences  in  the  centre  of 


Fig.  5. 
Section  of  ossifying  cartilage  magnified.    On  the  left  the  cells  are 
becoming  arranged  in  rows ;  while  to  the  right,  between  the  rows,  the 
earthy  material  is  being  deposited. 

the  shaft,  gradually  spreading  to  the  es  tremities,  in  which  there 
are  separate  points  of  ossification  ;  there  are  generally  three  such 
points,  one  for  the  shaft,  and  one  for  each  extremity,  the  develop- 
ing shaft  being  called  the  diaphysis,  the  eictremities  the  epiphyses. 
When  any  process  is  superadded,  as  the  trochanter  of  the  femur, 
which  possesses  a  distinct  point  of  ossification,  it  may  be  termed 
an  apophysis.  As  ossification  commences  in  the  shaft,  there  are 
for  some  time  after  birth,  interveqing  portions  of  un ossified 
cartilage,  marked  by  a  deep  ring  in  the  dried  long  bones  of 
young  animals  ;  they  disappear  at  variable  periods,  the  portions 
of  bone  hitherto  imperfectly  united  becoming  consolidated  into 
one  firm  mass.  The  bone  increases  in  length  by  growth  of  the 
unossified  ring,  uniting  the  shaft  and  epiphysis,  until  the  ring  fills 
up,  when  growth  is  completed.  Should  an  epiphysis  unite  with 
the  diaphysis  prematurely,  by  acceleration  of  the  process  of  ossifi- 
cation through  disease,  growth  being  thus  arrested,  the  bone  will  be 
shorter  than  its  fellow.      The  shaft  of  a  long  bone  increases  in 


SKELETON    OF    THE    HORSE.  17 

circumference  by  deposits  of  new  hone  on  its  external  surface, 
derived  not  from  eartilage,  but  from  membrane — the.  inner  layer 
of  the  periosteum,  which  has  been  termed  the  osteogenic  mem- 
Irane.  .In  the  periosteum  there  are  two  layers  or  strata — an 
outer,  strong  and  fibrous  ;  an  inner,  soft,  and  containing  osteo- 
blastic cells,  which,  after  undergoing  certain  changes,  produce 
layers  of  new  bone;  the  process  is  termed  intramembranous, 
as  opposed  to  intracartilaginous  ossification.  This  goes  on 
till  the  bone  has  reached  its  full  development,  when  Haversian 
systems  cease  to  be  formed,  and  then,  as  a  climax,  the  peri- 
pheral lamellae  are  formed,  and  the  medullary  canal  enlarges 
by  internal  absorption. 

In  flat  bones,  ossification  usually  radiates  from  a  centre,  and 
is  directed  by  the  membrane  investing  each  surface  of  the  bone; 
some  of  them  possess  numerous  apophyses.  Ossification  is 
completed  in  some  bones  much  earlier  than  in  others,  and  at 
birth  those  which  are  required  for  support  and  progression  are 
farthest  advanced. 

The  bones  of  the  cranial  vault  are  developed,  not  from  carti- 
lage, but  from  membrane.  In  early  foetal  life  the  brain  is 
covered  by  two  membranes,  closely  united— viz.,  the  pericranium 
and  dura  mater ;  between  these,  bone  becomes  developed  from 
radiating  ossific  centres. 

The  Skeleton. 

The  internal  framework  on  which  the  animal  body  is  built  is 
termed  the  Endoskeleton,  while  the  outer  casing  which  deter- 
mines the  shape  and  appearance  of  the  animal  is  the  Exoskele- 
TON ;  in  some  of  the  lower  animals  the  latter  assumes  the  form  of 
a  calcareous  case,  in  others  it  is  scaly,  in  others  again,  bony. 
The  exoskeleton  of  the  higher  animals  consists  of  the  skin  and  its 
appended  modifications,  which  will  be  described  in  a  future  sec- 
tion of  the  work.  By  the  term  skeleton  is  generally  understood 
the  endoskeleton,  or  bones  of  an  animal,  held  in  their  relative 
positions,  or  articulated  by  wires  or  screws,  in  which  case  all  the 
soft  tissues  are  first  removed,  and  the  preparation  is  termed  an 
artificial  skeleton  :  but  if  those  soft  structures,  whicli,  in  the 
living  animal,  join  the  bones  together,  are  allowed  to  remain, 
dried,  and  preserved,  then  the  preparation  is  a  natural  skeleton. 

As  the  skeleton  has  two  sides  or  halves,  the  majority  of  the 
bones  exist  in  pairs.  There  is,  however,  a  central  chain  of  single 
bones,  formed  by  the  back  bones   or  vertebrae  and  the   median 

C 


18 


OSTEOLOGY. 


FlQ.  6. 

SKELETON   OF  THE  HOESE  (Solidtjngula). 

Axial  Skeleton. 

the  skull. 

Cr*nial  Bones. — a.  Occipital.  1 ;  6,  Wormian.  1 ;  c.  Parietal,  2 ;  d.  Frontal,  2 ;  «,  Temporal,  2; 

Sphenoid.  1 ;  Ethmoid.  1 ;  Auditory  ossicles.  8. 

Facial  Bones.— h,  Nasal,  2:  g.  Lachrymal.  2  ;  /,  Malar,  2  ;  i,  Superior  maxilla,  2;  fc,  Premaxilla, 
2  ;  Palatine.  2  ;  Pterygoid.  2  :  Vomer.  1  :  Turbinals.  4  :  I,  Inferior  maxilla.  1 ;  Hyoid  (segments),  5. 
Teeth  :—m,  Incisors,  12  ;  n,  Canines.  4  :  o,  Molars.  24. 

The  Trunk.— p-v,  Cervical  vertebrse.  7 :  w,  Dorsal  vertebrae.  18 ;  x,  Lumbar  vertebrae,  6 ; 
y,  Sacrum,  1 ;  :,  Coccygeal  vertebrae  (variable),  18  ;  a'a',  Kibs,  36  ;  "  Sternum  (6-7  Stemebrae),  1 ; 
S  Costal  cartilages 

Appendioulah  Skeleton. 

rECTOR.^L   LIMB. 

e'.  Scapula,  2 ;  f.  Humerus,  2  ,  g',  Radius,  2  ;  A',  Ulna.  2.  Carpus  :— i',  Trapesium.  2  :  f.  Cunei- 
form, 2  :  V,  Lunar,  2 ;  tn'.  Scaphoid.  2 ;  n',  Unciform,  2 ;  o',  Magnum,  2 ;  p'.  Trapezoid,  2 ; 
g',  Pisiform.  2.  Metacarpus  r—r".  Large  bone.  2;  s'.  Small  bone,  4.  Digit :— it'.  Proximal 
phalanges,  2;  «/,  Median  phalanges,  2;  w'.  Distal  phalanges,  2;  f.  Large  sesamoids,  4:  Small 
sesamoids,  2. 


-6',  lUum. 


PELVIC   LIMB, 

!  ;  d'.  Ischium. 


: :  C,  Pubis,  2. 

",  Fibula,  2.     Tarsus  : 


Pelvis.— Ob  Innominatum 

The  Limb.—y',  Femur.  2  ;  y,  Patella.  2  ;  a".  Tibia,  2  ;  6",  Fibula,  2.  Tarsus  :— c".  Calcaneum,  2 : 
d",  Astragalus,  2 ;  e".  Cuboid.  2 ;  /",  Cuneiforme  magnum,  2 ;  g",  Cuneiforme  medium,  2 : 
h",  Cuneiforme  parvum.  2.  Metatarsus: — Large  bone.  2;  Small  bone,  4.  Digit :— Proximal 
phalanges,  2  ;  Median  phalanges,  2;  Distal  phalanges,  2  :  Large  sesamoids,  4  ;  Small  sesamoids,  2. 

The  Horse's  Skeleton,  as  here  considered,  consists  of  256  part*. 


SKELETON    OF    THE    HOESE.  !» 

seo-ments  of  tbe  head,  extending  the  whole  length  of  the  frame- 
work, and  uniting  its  lateral  halves.  But  even  these  single  bones 
present  the  same  shape  on  either  side  of  their  central  line;  hence, 
if  a  skeleton  were  divided  longitudinally,  exactly-  in  the  median 
plane,  the  two  halves  would  correspond.  This  "  right  and  left," 
or  double  arrangement  of  parts,  is  termed  bilateral  syratnetry. 

Anatomists  differ  as  to  the  number  of  bones  composing  the 
skeleton,  some  enumerating  all  ossific  bodies,  including  the  teeth 
and  sesamoids,  which  others  eliminate;  some,  again,  njgard  certain 
cranial  bones  as  single,  other  authorities  as  double.  It  is  of  little 
practical  importance  which  view  be  taken ;  it  will  be  found  that 
there  are  about  216  separate  bones;  or,  including  the  teeth,  256 
pieces  in  the  skeleton  of  the  horse. 

In  speaking  of  the  anatomical  position  and  relation  of  bones 
as  of  other  structures,  continual  reference  is  made  to  imaginary 
lines  or  planes.  The  skeleton  of  the  quadruped,  as  well  as  that 
of  man,  is,  in  an  anatomical  sense,  viewed  from  before ;  but  man, 
being  erect,  with  the  long  axis  of  his  body  in  a  vertical  position, 
whilst  that  of  the  quadruped  is  horizontal,  corresponding  organs 
do  not  always  present  themselves  to  observation  from  the  same 
point  of  view.  With  reference  to  quadrupeds,  imaginary  planes 
are  supposed  to  lie  as  follows  : — A  longitudinal  median  vertical 
plane  descends  through  the  centre  of  the  head,  vertebral  chain, 
and  trunk,  midway  between  the  right  and  left  extremities,  to 
the  ground,  dividing  the  body  into  two  exact  halves ;  right  and 
left  lateral  vertical  planes  are  placed  parallel  to  the  former,  but 
external  to  the  body ;  at  right-angles  to  the  above  an  anterior 
vertical  plane  is  placed  in  front,  and  a  posterior  vertical  one 
behind ;  a  superior  horizontal  plane  lies  above  the  body,  between 
the  anterior  and  posterior  vertical  planes  ;  while  parallel  with 
the  superior  is  an  inferior  horizontal  plane,  placed  under  the  feet. 
The  external  surface  of  an  organ  or  region  is  that  which  faces  the 
lateral  plane  on  the  side  where  the  organ  is  situated.  The 
internal  surface  faces  the  median  plane  of  the  body,  the  anterior 
surface  the  anterior  vertical,  the  posterior  surface  the  posterior 
vertical  plane,  while  the  superior  and  inferior  surfaces  are  those 
facing  their  respective  superior  and  inferior  planes.  This  imagin- 
ary index  may  be  applied  to  any  region,  as  well  as  to  the  entire 
body. 

Modifications  of  these  terms  are  used  when  it  is  requisite  to 
point  out  the  precise  situation  of  a  structui-e.      For  example,  take 


20  OSTEOLOGY. 

the  anterior  limb,  and  suppose  it  encompassed  by  the  planes  ut 
supra.  If  wje  wish  to  describe  the  situation  of  any  object  on  the 
upper  part  of  its  lateral  region,  the  term  supero-lateral  would  be 
used;  if  the  object  were  situated  at.  the  lower  lateral  part,  then 
infero-lateral.  Similar  modifications  of  terms  are,  of  course, 
applicable  to  the  anterior  and  posterior  surfaces.  Supero-anterior 
implies  the  superior  part  of  the  anterior  region,  and  antero- 
superior  the  anterior  part  of  the  superior  region.  For  description, 
structures  are  frequently  divided  into  two  or  more  parts  ;  thus 
we  allude  to  the  superior,  middle,  or  inferior  third  of  an  object. 
The  end  of  a  structure  which  is  nearest  to  the  vertebral  column 
is  often  termed  the  x>roximal,  while  the  remote  end  is  termed 
the  distal  extremity. 

DIVISION    OF    THE    SKELETON. 

The  limbs,  with  their  media  of  attachment,  form  the 
Appendiculak  Skeleton  ;  while  the  remaining  portion  of  the 
structure,  consisting  of  the  skull,  vertebrae,  ribs,  and  breast-bone, 
is  called  the  Axial  Skeleton.  By  many  authorities  the  skull 
is  regarded  as  being  formed  of  a  number  of  modified  vertebrae, 
while  the  ribs  and  breast-bone,  or  sternum,  are  considered  parts 
of  complete  vertebral  segments.  Taking  this  view,  the  term 
axial  skeleton  would  be  synonymous  with  vertebral  column.  In 
this  work  we  first  describe  the  axial  skeleton,  dividing  it  into 
the  vertebral  column  and  the  skull,  afterwards  treating  of  the 
appendicular   skeleton.      The   following   Table   will   exhibit   this 

division  : — 

Axial  Skeleton. 

Cervical  E,egion. 

,  Dorsal  Region.   < 
Vertebral;  I  Sternum. 

Column.    \  Lumbar  Region. 

/  Sacral  Region.  • 

V  Coccygeal  Region. 

f  Cranium 

t  Face. 

Apjjendicular  Skeleton. 

Pectoral  Arcli  and  Limb 
Pelvic  Arch  and  Limb. 


Skill 


EXPLANATION  OF  PLATE  L 


Skeleton  of  the  Horse, 

Showing  its  relation  to  the  convour  of  the  animal,  viewed  laterally. 


A.  Temporal  fossa. 

B.  Inferior  maxilla. 

C.  Atlas. 

D.  Dentata. 

E.  Cervical  vertebrae. 

F.  Dorsal        do. 

G.  Lumbar  do. 
H.  Sacral  do. 
I.  Coccygeal  do.'' 
J.   Scapula. 

K.  Humerus. 
L.  Radius. 
L'.  Ulna. 
M.  Carpus. 
N.  Trapezium. 
0.  Metacarpus. 
P,  b.  Os  suffraginis. 
Q,  c.  Sesamoids. 
R,  d.  Os  coronae. 
S,  e.  Os  pedis. 
TT.  Ribs. 
U.  Ilium. 
V,  Femur. 
X.  Patella. 
Y.  Tibia. 
V.   Fibula. 


Z.  Tarsus. 
a.  Metatarsus. 

/.  Ligamentum  nucliae,  funicular  por* 
tion.    /'.  Laraellar  portion. 

1.  Zygoma. 

2.  Orbital  fossa. 

3.  Nasal  peak. 

4.  Incisor  teetli. 
4'.  Canine  teeth. 

5.  Molar  teeth. 

S.  External  humeral  trochanter. 
7  7.  Scapular  fosste. 

8.  Coracoid  apophysis. 

9.  Cartilage  of  prolongation. 

10.  Deltoid  ridge,  and  external  tuber- 

osity. 

11.  Olecranon. 

12.  Costal  cartilages. 

13.  Anterior  iliac  spine. 

14.  Ischium. 

15.  Trochanter  major. 

16.  Trochanter  minor. 

18.  Anterior  tibial  tuberosity. 

19.  Calcaneum. 

2020.  Small  metacarpal  and  metatarsal, 
or  splint  bones. 


true  vertebile.  21 

Axial  Skeleton. 

VERTEBRAL    COLUMi«'. 

The  vertebral  or  spinal  column  may  be  considered  the  found- 
ation of  the  skeleton,  from  which  all  othei'  parts  proceed.  Ex- 
tending the  whole  length  of  the  body,  it  consists  of  a  series  of 
single  bones,  termed  vertehrce,  firmly  united,  and  it  presents 
a  succession  of  curves ;  thus,  in  the  horse,  the  neck,  back,  and 
croup  are  usually  curved,  while  the  loins  are  nearly  straight. 

The  vertebral  chain  may  be  divided  into  five  regions,  exclusive 
of  the  cranial  portion,  which  we  regard  collectively  as  the  skull. 
These  are  the  cervical,  dorsal,  lumbar,  sacral,  and  coccygeal — 
respectively  the  regions  of  the  neck,  back,  loins,  croup,  and  tail  ; 
and,  while  all  possess  certain- points  of  conformation  in  common, 
special  peculiarities  distinguish  the  vertebrae  of  any  one  region 
from  those  of  another. 

Vertebras  are  either  true  or  false;  true  vertebrae  possess 
certain  typical  parts,  which  they  retain  throughout  the  life  of 
the  animal,  and  they  never,  in  health,  unite  by  ossification ; 
while  false  vertebrae  either  do  not  possess  the  essential  characters 
of  true,  or  they  may  become  so  united. 

TRUE    VERTEBRAE. 

A  true  vertebra  consists  of  a  body  or  centi'uni,  an  arch,  called 
the  neural  arch,  notches,  and  spinous,  transverse,  and  articular 
processes.  The  body  is  the  solid  block  of  bone  on  which  all  the 
other  parts  are  built,  and  which,  in  quadrupeds,  lies  below  the 
spinal  canal.  Its  anterior  end  is  convex,  and  its  posterior 
correspondingly  concave,  both  being  discs  of  compact  bone 
roughened  for  the  attachment  of  the  soft  intervertebral  substance. 
Its  upper  or  spinal  surface  is  flattened  or  slightly  concave,  its 
inferior  surface  being  convex,  and  sometimes  terminating  in  a 
spinous  process  or  prominent  ridge. 

The  neural  arch  or  ring  rises  from  the  supero-lateral  surfaces 
of  the  body  by  two  processes  of  bone  termed  pedicles,  from  each 
of  which  a  plate  of  bone,  the  lamina,  expands  and  passes  inwards, 
the  iinion  of  the  laminae  in  the  median  line  completing  the  arch, 
which  encloses  the  neural  canal  or  spinal  foramen. 


22 


OSTEOLOGY. 


The  notches  are  excavations  in  the  anterior  and  posterior  sur- 
faces of  each  pedicle,  so  placed  that  when  the  vertebras  are  in  situ 
the  botch  in  the  posterior  part  of  one  pedicle  corresponds  with 
that  in  the  anterior  of  the  next,  the  two  forming  a  large  opening, 
called  the  intervertebral  foramen,  which  leads  to  the  neural 
canal  and  gives  passage  to  the  spinal  nerve  and  blood-vessels. 

Each  true  vertebra,  with  the  exception  of  the  two  anterior 
cervical  ones,  has  four  oblique  or  aHicular  processes  (zyga- 
pophyses)  on  the  superior  and  lateral  parts  of  the  arch.  The 
faces  of  the  anterior  of  these  processes  are  directed  upwards  and 
inwards,  those  of  the  posterior  downwards  and  outwards ;  as 
their  name  implies,  they  articulate  and  form  joints  with  the 
corresponding  processes  of  contiguous  vertebrae.  In  some  of  the 
dorsal  and  lumbar  segments  of  certain  animals,  the  anterior 
zygapophyses  have  processes  which  project  above  the  level  of  the 
articular  facets;  these  are  the  mammillary  processes  (meta- 
pephyses). 

The  transverse  processes  (diapophyses),  one  on  each  side, 
spring  from  the  sides  of  the  body  and  pedicle,  and  are  projec- 
tions varying  much  in  size  and  shape  in 
the  different  regions.  Between  the  anterior 
zygapophysis  and  the  metapophysis  in  some 
animals  there  may  be  another  small  emin- 
ence projecting  backwards  (anapophysis). 

The  spinous  processes  are  superior  and 
inferior.  The  superior  or  neural  spine 
(neurapophysis),  formed  by  the  union  of  the 
laminee,  and  surmounting  the  centre  of 
the  arch,  is  sometimes  of  great  size  and 
strength,  but  varies  much  in  development 
in  the  different  regions  of  the  same  animal. 
The  inferior  (hypapophyses)  are  for  the 
most  part  rudimentary,  and  can  scarcely  be 
said  to  exist,  except  in  the  cervical  region, 
where  they  project  from  the  inferior  central 
line  of  the  bodies. 

The  centra  or   bodies  of   the  vertebrae, 
placed  in  natural  apposition,  thus  form  a 
central  bony  column,   to  which  the  arches 
and  processes  are   attached  ;   the   arches,   with   their  connecting 
ligaments,  form  superiorly  a  cavity,  the  spinal  or  neural  canal. 


'^^.f^ 


Fig.  7. 

Diagramatic  transverse  sec- 
tion from  the  skeleton  of  a 
mammalian  thoiax,  showius 
the  chief  features  of  a  perfect 
vertebral  segment.  1,  Neural 
spine,  2,Lamina(neurapophy- 
sis);  3,  Pedicle;  4, Neural  arch; 
5.  centrum;  6,  Inferior  Spine 
(hypapophysis) :  7  7,  Haemal 
arch ;  8,Rib(pleurapophysis); 
9,  Costal  cartilage  (haema- 
pophysis)  ;  10,  Sternebra  . 
11,  Hseraal  spine. 


CERVICAL    VERTEBRA.  23 

-which  extends  from  the  head  to  the  tail,  and  contains  the  spinai 
cord,  with  its  membranes  and  blood-vessels;  the  articular  pro- 
cesses strengthen  the  connections  of  the  vertebrae,  while  the 
spinous  and  transverse  processes  are  levers  to  which  muscles  are 
attached,  their  development  having  great  influence  on  the  physical 
conformation  and  capabilities  of  the  animal  The  ribs  may  be 
regarded  as  continuations  of  the  dorsal  transverse  processes ;  they 
form  the  inferior  or  hasmal  arch  of  their  own  region. 


FALSE   VERTEBR2E. 

The  false  vertehrce  are  found  in  the  sacrum,  which  con- 
sists of  vertebral  segments  united  by  the  ossification  of  their 
connecting  material,  and  in  the  coccyx,  the  skeleton  of  which 
consists  of  rudimentary  or  imperfectly-developed  vertebrae.  The 
sacral  segments  in  the  early  stages  of  life  are  separable,  and 
they  present  all  the  characteristics  of  true  vertebrae. 


CERVICAL   VERTEBRiE. 

General  Features. 
(Fia.  8.) 

There  are  seven  cervical  vertehrce  in  all  the  Mammalia,  with 
the  exception  of  the  Three-toed  Sloth,  which  has  nine,  and  one  of 
the  Sea-cows,  which  has  six.  They  are  numbered  in  order  from 
the  head,  the  first  receiving  the  special  name  of  atla,8,  and  the 
second  that  of  axis  or  vertebra  dentata  ;  these,  with  the  sixth  and 
seventh,  differ  from  the  rest,  which  are  essentially  alike. 

The  centra  or  bodies  of  the  cervical  vertebrae  are  larger  and 
longer  than  those  of  any  other  true  vertebrae,  and  frequently 
measure  upwards  of  four  inches  in  length  ;  they  are  quadrangular 
in  shape,  their  anterior  extremity  or  head  being  convex  and  some- 
what heart-shaped,  with  the  apex  downwards,  while  the  posterior 
extremity  presents  a  corresponding  cup-hke  cavity.  The  flexi- 
bility of  the  neck  is  partly  due  to  these  convexities  and  cavities, 
which  are  more  pronounced  in  the  cervical  region  than  in  other 
parts  of  the  column.  The  superior  surface  is  flattened,  and  pre- 
sents, close  to  the  pedicle  on  each  side,  a  distinct  furrow,  which 
contains  the  spinal  vein ;    these  lateral   furrows  are  united  by 


24 


OSTEOLOGY. 


means  of  a  central  transverse  furrow,  and  partly  covered  by  a  thin 
bony  plate,  to  which  the  superior  common  ligament  is  attached. 
The  inferior  surface  presents  a  longitudinal  process  or  ridge,  the 
inferior,  spinous  process,  which  increases  in  size  as  it  approaches 


8  o  'o  ^  I  o  g  s 

"  g  I  «  I  2  I  2 


^   o   a   a 


a  a. 


o  £ 

o  «  '^"  '^.  I  .I  S  ^ 


S  ".  g  ^-  6  §•  I  £ 


l|  S3  1-2  S  s  f.a 


the  posterior  end  of  the  bone,  where  it  terminates  in  a  projecting 
tuberosity,  which  gives  attachment  to  the  longus  colli  muscle. 
The  lateral  surfaces  of  the  body,  above  the  inferior  spine,  are 
flattened,  and  somewhat  excavated. 


CERVICAL    VERTEBRA.  25 

The  superior  spinalis  processes  or  neural  spines  are  mostly 
Tudimentaxy,  and  rise  from  the  centre 
•of  the  quadrilateral  space  between 
the  oblique  processes.  They  are 
bifid  posteriorly,  the  ligamentum 
nuchse  and  spinalis  colli  muscle 
being  attached  in  the  bifurcation. 

The  transverse  processes,  broad, 
short,  strong,  and  irregular  in  shape,  '         p^^  g 

pass  directly  outwards,  and  divide  ^^^^  ^^^^  ^^^  ^^  ^  ^^  ^^^ 

into  two  parts one    projecting  an-  bra  of  a  Horse,    l,  JSreural  spine  ;  2,  Ah- 

.     p     .      1  1,1  ,1  ,  terior  oblique  processes;  3,  Posterior 

terO-infenorly,  and  the  other  pOSterO-  oblique  processes;  5,  convex  anterior  end. 

inferiorly.     They  increase  in  size  as       and  9,  concave  posterior  end  of  the  cen- 

*'  "'  1        11        /.  trum;  6,  Anterior  ends  of  tran-sversepro- 

they   extend    backwards,    and    all     of  cesses; and  7,  Posterior  end  of  nght  one; 

them,       except       the       seventh,       are  S,  inferior  process,  or  hypapophysi.. 

pierced  by  the  vertebral  foramen,  through  which  pass  the  verte- 
bral artery  and  vein.  These  processes  give  attachment  to  the 
serratus  magnus,  splenius,  longus  colli,  intransversalis  colli,  levator 
humeri,  and  other  muscles  acting  upon  the  head  and  neck. 

The  articular  processes,  larger  than  in  any  other  region,  have 
flattened  oval  articular  surfaces  ;  the  anterior  two  look  upwards 
and  inwards,  while  the  posterior  look  downwards  and  outwards. 
The  articular  processes  of  the  posterior  five  cervical  vertebrae  give 
attachment  to  the  complexus  major,  trachelo  mastoideus,  and 
spinalis  colli  muscles. 

The  arches,  stronger  than  in  any  other  region,  enclose  the  spinal 
canal,  which  progressively  increases  in  size  in  the  direction  of 
the  dorsal  vertebrae,  its  vertical  diameter  being  the  greater.  The 
notches'  of  the  three  posterior  cervical  vertebrae  are  also  larger 
than  the  rest. 

Viewed  in  situ,  it  is  seen  that  the  transverse  processes  of  the 
three  central  cervical  vertebrae  are  largest  and  strongest,  with  the 
exception  of  that  of  the  first,  and  they  can  be  detected  under 
the  investing  mus<iles  in  the  living  animal ;  also  that  the  bodies 
progressively  diminish  in  length,  and  increase  in  breadth  and 
depth  from  the  second  backwards. 

The  first,  second,  sixth,  and  seventh  cervical  vertebrae  having) 
features  peculiar  to  themselves,  require  special  notice. 


26  OSTEOLOGY. 

SPECIAL  CERVICAL   VERTEBRA. 

The  Atlas. 

The  First  cervical  vertebra  is  called  tlie  Atlas,  because  in 
human  anatomy  it  supports  the  head ;  in  quadrupeds  the  head 
is  suspended  from  it.  It  presents  no  well-defined  body,  but 
consists  of  a  strong  ring  of  bone,  the  superior  surface  of  -which  is 
convex,  with  a  slight  longitudinal  elevation  in  the  median  line, 
from  which  the  alee  or  wings  slope  downwards  and  backwards. 
The  wings  are  large,  flat  transverse  processes,  wider  than  those 
of  any  other  true  vertebra,  and  they  terminate  in  rough  convex 
margins,  which  may  be  plainly  felt  through  the  skin  in  the  living 
animal  ;  they  give  insertion  to  portions  of  the  levator  humeri, 
splenius,  trachelo  mastoideus,  and  obliquus  capitis  posticus  muscles, 
and  are  always  largely  developed  in  the  carnivora. 

Superiorly,  each  ala  exhibits  three  foramina ;  the  posterior  is 
the  largest,  and  corresponds  to  the  vertebral  foramen,  giving 
passage  to  the  anastomotic  branch  of  the  occipital  artery.  The 
two  anterior  foramina  are  joined  by  a  short,  deep  depression, 
the  alar  gutter  ;  the  external  foramen  gives  passage  to  the 
occipital  artery,  vein,  and  nerve,  while  the  internal  passes  through 
the  ring  into  the  neural  canal,  representing  the  intervertebral 
foramen,  and  through  it  pass  the  cerebro-spinal  artery,  and  the 
first  spinal  nerve. 

The  inferior  surface  of  the  atlas  is  convex  centrally,  and 
presents  posteriorly  a  short,  obtuse  eminence,  which  represents 
the  inferior  spine,  this  is  the  tubercle  of  the  atlas  to  -which  the 
tendon  of  the  longus  colli  muscle  is  attached.  On  each  side  of 
the  central  convexity  we  find  a  large  concave  space  limited  exter- 
nally by  the  ala.  The  anterior  surface  presents  two  notches 
and  two  articular  depressions.  The  notches  are  of  great  size,  and 
contain  the  superior  and  inferior  suspensory  ligaments — one 
being  above,  and  the  other  below,  the  spinal  canal.  The  arti- 
cular glenoid  cavities  receive  the  condyles  of  the  occipital  bone, 
and  are  each  constructed  of  a  superior  and  an  inferior  continuous 
surface  ;  the  inferior,  r^resenting  the  convex  head  of  other 
vertebrae,  is  concave  ;  while  the  superior,  nearly  flat,  represents 
the  oblique  processes.  A  prominent  bony  ridge,  to  which  is 
inserted  the  investing  <^t  capsular  ligament,  surrounds  the  anterior 
border  of  the  bone.      The  posterior  surface  presents  a  somewhat 


THE    DENTATA.  27 

triangular  outline  ;  its  inferior  margin  is  excavated  to  receive  the 
odontoid  process  of  the  second  vertebra,  while  the  superior  is 
thin,  and  roughened  for  ligamentous  insertion,  and,  on  each  side, 
a  broad  slightly  convex  articular  surface  represents  the  posterior 
oblique  processes.  This  surface  is  bounded  externally  by  a  tidge, 
which  gives  insertion  to  the  capsular  ligament ;  and  internally  it 
is  separated  by  a  similar  ridge  from  the  spinal  canal. 

The  spinal  foramen  of  the  atlas  is  very  large,  in  order  that  the 
spinal  cord  may  be  preserved  from  injury  during  the  extensive 
,motions  which  take  place  between  the  head  and  neck.  Its  floor 
is  divided  by  a  transverse  ridge  into  two  portions,  the  anterior  of 
which  is  roughened  for  the  attachment  of  ligaments,  the  posterior 
being  smooth  for  the  articulation  of  the  odontoid  process.  Its 
roof  is  smooth,  and  penetrated  by  two  foramina  for  the  passage  of 
an  artery  and  nerves,  and  its  sides  have  each  an  excavation  in 
which  a  venous  sinus  is  lodged ;  a  foramen  from  this  excavation 
opens  on  the  inferior  surface  of  the  ala,  and  transmits  a  vein  from 
the  sinus. 

The  atlas  has  three  articular  processes, — two  for  the  occipital 
condyles,  and  one  for  the  axis, — all  of  which  form  true  joints, 
the  atlas  being  the  only  vertebra  possessing  none  but  true 
articulations. 

The  Dentata. 

The  Second  vertebra  is  called  also  the  axis,  because  the  head 
rotates  upon  it,  also  the  vertebra  dentata,  from  a  process  which, 
in  the  corresponding  human  bone,  somewhat  resembles  a  tooth  ire 
shape,  and  is  called  the  odontoid  process  ;  it  is  situated  on  the 
anterior  end  of  the  centrum,  projecting  forwards  into  the  ring  of 
the  atlas,  and  around  it  the  head  and  atlas  rotate.  In  the  horse 
the  under  surface  of  this  process  is  smooth  and  rounded,  and  the 
upper  roughened  and  excavated,  for  the  attachment  of  the 
odontoid  ligaments  ;  laterally,  it  terminates  in  a  broad,  oval, 
somewhat  convex  surface,  which  represents  the  oblique  processes, 
and  articulates  with  the  posterior  surface  of  the  atlas ;  these 
articular  shoulders  being  bounded  by  a  ridge,  to  which  the 
capsular  ligament  is  attached. 

The  neural  spine  of  the  axis  springs  from  a  very  strong  arch, 
and  is  nearly  as  long  as  the  body,  which  is  longer  than  that  of 
any  other  true  vertebra ;  this  spine  is  convex,  and  consists 
of  lateral  halves,   united    anteriorly   into    a  strong  rough   crest, 


28  OSTEOLOGY. 

but  bifurcating  posteriorly  into  ridges,  which  terminate  in  the 
oblique  processes.  The  inferior  spine  arises  from  a  notch  in 
the  inferior  part  of  the  odontoid  process ;  it  is  broad  and  rough 
anteriorly,  but  contracts  into  a  sharp  spine,  which  terminates  in 
a  roughened  tubercle  posteriorly.  The  transverse  processes,  the 
smallest  in  the  cervical  region,  are  single,  and  project  outwards 
and  backwards  ;  they  are  pierced  by  very  small  vertebral  foramina. 
The  spinal  canal  is  somewhat  narrow,  and  instead  of  notches, 
there  are  two  oval  foramina  anteriorly  for  the  passage  of  the 
spinal  nerves.  The  posterior  parts  of  the  body  and  arch  do  not 
materially  differ  from  those  of  the  other  cervical  vertebrae. 

In  the  horse  the  atlas  and  axis  do  not  approximate  above  the' 
spinal  canal,  and  there  is  a  considerable  space  between  them,  the 
atlo-axoid  space,  which  is  covered  by  soft  structures  only  ;  and 
here  the  operation  of  "  pithij?g  "  is  easily  performed. 

The  Tivo  Last  Segments. 

The  Sixth  vertebra  has  a  much  shorter  body  than  those 
anterior  to  it,  and  is  destitute  of  an  inferior  spine.  Its  trans- 
verse processes  consist  of  three  lateral  divisions,  and  its  vertebral 
foramina,  notches  and  spinal  canal  are  of  great  size. 

The  Seventh  vertebra,  or  Vertebra  prominens,  the  shortest  of 
the  series,  is  very  strong,  and  has  an  elevated  neural  spine,  point- 
ing upwards  and  forwards,  but  scarcely  the  trace  of  an  inferior 
one.  Its  oblique  processes  resemble  the  four  preceding ;  its 
transverse  processes  are  small,  and  have  usually  no  vertebral  fora- 
mina, while  its  notches  and  spinal  canal  are  larger  than  in  any 
other  of  the  last  six  cervical  vertebrae.  On  each  side  of  its 
body,  posteriorly,  it  presents  a  depression  which,  with  a  corre- 
sponding depression  on  the  first  dorsal  centrum,  forms  a  cup  for 
the  articulation  of  the  first  rib.  Altogether  it  closely  resembles 
in  character  the  first  dorsal  vertebra. 

DORSAL    VERTEBRA. 
(Pl.  I.  F.) 

These  vertebrae,  of  which  there  are  eighteen  or  rarely  nineteen, 
always  correspond  in  number  with  the  pairs  of  ribs,  and  in  the 
horse  form  the  weight-bearing  portion  of  the  column,  extending 
over  the  whole  length  of  the  chest.  Their  bodies,  the  smallest 
of  the  true  vertebrae,  are  short,  thick,  and  somewhat  semicircular 


DORSAL    VERTEBRAE.  29 

ia  form,  each  presenting  a  middle  ridge  along  its  under  surface, 
to  which  the  inferior  common  ligament  is  attached.  The  superior 
surface  of  the  body,  which  forms  the  floor  of  the  spinal  canal,  is 
flattened  and  quadrilateral,  presenting  longitudinal  furrows  for 
the  spinal  vessels,  and  often  a  central  transverse  one,  partially 
covered  by  a  bony  plate.  The  anterior  extremity  presents  a 
slightly  convex  head,  on  the  superior  and  Uteral  aspect  of  which 
is  a  semicircular  depression  corresponding  with  another  on  the 
posterior  extremity  of  the  vertebra  in  front,  so  that  together  they 
form  a  cup-shaped  cavity  for  the  articulation  of  a  rib,  each  articu- 
lating with  one-half  of  the  head  of  the  rib.  The  posterior 
extremity  is  concave,  to  articulate  with  the  contiguous  bone,  and 
has  on  each  side  an  articular  depression  similar  to  those  on  the 
anterior  extremity.  The  transverse  processes,  rising  from  the 
sides  6f  the  arches,  are  small  ;  superiorly  and  anteriorly  they  are 
roughened  for  muscular  attachment,  and  at  its  posterior  inferior 
part,  each  presents  a  flat,  smooth  facet  which  articulates  with 
the  tubercle  of  the  next  anterior  rib. 

The  neural  spines,  larger  than  in  any  other  region,  vary  much 
in  size,  shape,  •  and  direction,  the  first  twelve  being  directed 
backwards,  the  next  three  nearly  upright,  and  the  last  three 
forwards  ;  their  length  gradually  increases  to  the  fifth,  which  is 
usually  the  longest,  and  then  decreases  to  the  fourteenth,  which 
is  generally  somewhat  shorter  than  those  behind  it ;  the  first  is 
small  and  sharp,  and  the  second,  which  is  abruptly  bent  back- 
wards, is  very  strong  ;  the  summits  of  the  next  six  or  seven  are 
flattened,  roughened,  and  expanded  laterally,  assuming  a  bifid 
appearance,  giving  greater  surface  for  the  attachment  of  muscles 
and  the  great  suspensory  ligament  of  the  head  and  neck,  the 
ligamentum  nuchce.  The  lateral  surfaces  are  convex  and 
slightly  roughened,  the  anterior  borders  being  thin  and  serrated, 
while  the  posterior,  of  the  higher  spines  especially,  are  broad  and 
concave,  becoming  cleft  as  they  approach  the  oblique  processes. 

The  oblique  processes  are  small,  and  their  facets  are  more 
horizontal  than  in  the  cervical  region,  and  closer  together.  The 
pedicles  are  short  and  strong,  and,  with  the  exception  of  the 
anterior  four  or  five,  possess  notches  on  their  posterior  edges 
only  ;  backwards,  we  find  these  notches  become  more  and  more 
closed  in,  until  posteriorly  there  are  foramina  in  lieu  of  notches. 
The  arch,  and  consequently  the  spinal  canal,  are  small,  the 
laminae  passing  almost  directly  inwards  from  the  pedicles. 


30  OSTEOLOGY. 

An  ordinary  dorsal  vertebra  has  twelve 'articnlar  surfaces — viz.^ 
three  anterior  and  three  posterior,  as  in  the  cervical,  and  three 
at  each  side  ;  of  the  latter,  two  are  for  the  heads  of  two*  ribs, 
and  the  third  for  the  tubercle  of  the  anterior  rib.  The  depres- 
sions for  the  heads  of  the  ribs  are  deepest  between  the  anterior 
vertebrae,  and  gradually  grow  shallower,  in  the  two  last  becoming 
continuous  with  the  facet  on  the  transverse  process.  The 
eighteenth  segment,  being  attached  to  but  one  rib  on  each  side, 
has  eight  articulating  surfaces  only. 

Viewing  the  dorsal  vertebrae  in  connection,  it  is  seen  that  the 
spines  diminish  from  the  fifth  backwards,  and  the  vertebrae 
themselves  grow  narrower.  The  first  exhibits  some  of  the 
characters  of  a  cervical  vertebra,  ^-?.d  the  second  has  a  short 
body,  with  transverse  and  anterior  oblique  processes  formed 
on  the  same  bony  projection,  and  a  neural  spine,  short,  convex 
anteriorly,  and  more  bent  than  any  other  in  the  vertebral  chain. 
The  first  thirteen  form  the  skeleton  of  the  withers,  and,  when 
well  developed,  the  height  of  their  spines  increases  the  surface  for 
muscular  attachment,  and  also  affords  greater  leverage. 


LUMBAR  VERTEBRA. 
(PL,  I.  G.) 

These  form  the  skeleton  of  the  loins,  and  are  shorter  in  the 
horse  in  proportion  to  his  size,  than!  in  other  animals.  Their 
number  is  six  usually,  sometimes  five,  in  the  horse,  siz  in  the 
mule,  generally  five  in  the  ass,  and  also,  it  is  said  in  the  Arab 
horse.  Their  bodies,  intermediate  in  length  between  the  cervical 
and  the  dorsal,  are  thick  and  strong,  the  three  anterior  being 
flattened  superiorly  and  late:^ally,  and  possessing  a  strongly- 
developed  median  ridge ;  the  three  posterior  ones  are  convex 
laterally,  and  flattened  above  and  below.  More  motion  being 
required  in  the  loins  than  in  the  back,  the  anterior  extremities 
of  the  centra  of  the  lumbar  vertebrae  are  more  convex,  and  the 
posterior  extremities  more  concave  than  those  in  the  dorsal 
region.  The  arches  enclose  a  large  semicircular  spinal  canal, 
and  with'  one  or  two  exceptions  possess  both  anterior  and  posterior 
notches.  The  neural  spines  are  strong,  broad,  and  flattened 
laterally  ;  they  incline  slightly  forwards,  are  about  the  same  length 
as  the  posterior  dorsal  spine,  and  have  sharp  anterior  and  posterior 


THE    SACEUM.  31 

•edges,  with  rough  expanded  extremities  ;  they  increase  slightly  in 
height,  and  diminish  in  strength  backwards. 

The  transverse  processes,  longer  than  the  corresponding  pro- 
cesses in  any  other  region,  are  broad  and  flat  with  rounded 
extremities,  and  extend  nearly  horizontally  from  the  bodies ; 
the  central  are  tBe  largest,  the  two  first  inclining  a  little  back- 
wards, and  the  three  last  slightly  forward.  The  last  two  of 
these  processes  articulate  with  each  other  by  means  of  facets,  and, 
in  advanced  age  sometimes  become  united  by  ossification,  the 
sixth  articulating  in  a  similar-,  manner  with  the  sacrum.  The 
oblique  jirocesses  project  farther  from  the  arch  than  those  of  the 
dorsal  region ;  the  articular  facets  of  the  anterior  ones  are 
concave  and  directed  inwards,  while  those  of  the  posterior  are 
convex  and  directed  outwards. 

The  first  four  lumbar  vertebrae  have  six,  the  typical  number  of 
articular  surfaces,  the  fifth  having  in  addition  one  on  each  posterior 
border  of  its  transverse  processes,  and  the  sixth  one  on  ea6h 
border,  anterior  and  posterior,  of  these  processes,  or  ten  in  all. 


False  Vertebra, 
the  sacrum. 

(PL.  I.  H.) 

This,  the  bone  of  the  croup,  is  a  single,  somewhat  triangular- 
shaped  bone,  consisting  of  five  false  vertebrae  united,  in  the  young 
animal  by  articulation,  and  in  the  adult  by  ossification  ;  it  con- 
tains the  continuation  of  the  spinal  canal,  forms  the  roof  of  the 
pelvis,  and  has  articular  surfaces  by  which  the  pelvic  arches  are 
attached,  and  in  the  horse  these  are  the  only  articular  connec- 
tions between  the  axial  and  appendicular  skeletons.  Its  direction 
varies  somewhat  according  to  the  breeding  of  the  animal ;  in 
lightly-made,  highly-bred,  and  well-formed  animals  its  long  axis 
is  usually  placed  in  a  nearly  horizontal  line,  while  in  horses  of 
coarser  breed  its  coccygeal  extremity  is  often  considerably  lower 
than  the  other,  thus  giving  a  drooping  appearance  to  the  contour 
of  the  croup.  It  presents  for  consideration  superior  and  inferior 
surfaces,  two  lateral  borders,  and  anterior  and  posterior  extremities. 

The  superior  surface  is  irregularly  convex,  with  the  flat-topped 
spines  of  its  vertebral  segments  running  along  its  centre,  decreas- 
ing in  height,  but  increasing  in  breadth  as  they  extend  backwards. 


32  OSTEOLOGY. 

In  a  groove  at  their  base,  opposite  the  interspinous  spaces,  are 
the  four  superior  sacral  foramina,  which  give  exit  to  the  superior 
branches  of  the  sacral  nerves.  An  irregularly-elevated  ridge, 
external  to  the  grooves,  marks  the  division  between  the  superior 
and  inferior  surfaces  of  the  bone.  The  infeinor  or  pelvic  surface 
is  smooth  and  rather  concave  ;  at  its  anterior  end  is  a  trans- 
verse elevation. 'the  sacral  promontory,  not  very  pronounced  in  the 
horse,  and  crossing  the  bone  transversely  are  four  slightly-elevated 
lines,  which  show  the  connections  between  the  original  segments. 
Between  these  lines,  and  close  to  the  borders  on  each  side  are 
the  four  large  foramina  through  which  pass  the  inferior  branches 
of  the  sacral  nerves,  and  at  the  anterior  end  two  notches,  which 
correspond  with  similar  notches  in  the  last  lumbar  vertebra,  and 
form  the  foramina  through  which  the  first  sacral  nerves  find 
their  exit. 

The  anterior  extremity  or  hase  is  almost  entirely  articular  ; 
the  central  part,  oval  and  convex,  articulates  with  the  last  lumbar 
vertebra,  and  above  it.  is  the  spinal  canal  surmounted  by  the 
articiilar  processes.  The  lateral  parts  are  the  thick  expanded 
transverse  processes  which  terminate  in  sharpened  extremities, 
and  contain  two  broad  facets  for  articulation  with  those  on  the 
last  lumbar  transverse  processes.  The  'posterior  extremity  or 
apex  presents  the  diminished  spinal  canal  in  its  centre,  with  the 
last  spinous  process  above  it,  and  below  the  flat  surface  which 
articulates  with  the  first  bone  of  the  coccyx,  while  the  notches  and 
the  sacral  cornua  are  on  its  sides. 

The  lateral  borders,  anteriorly,  are  roughened  for  attachment 
to  the  iliac  bones  under  which  they  lie,  and  with  which  they 
form  the  sacro-iliac  joint ;  posteriorly,  they  are  roughened  for 
the  attachment  of  the  sacro-sciatic  ligaments,  and  terminate  in 
small  transverse  processes — the  sacral  cornua. 

The  sacrum  has  five  articular  surfaces  on  its  base,  one  on  each 
side,  and  one  on  its  apex.  Its  spinal  canal  is  somewhat  triangular 
in  shape,  and  decreases  much  in  size  posteriorly. 


THE    COCCYX. 

(PL.  I.  I.) 

The  coccygeal  or  caudal  vertehrce*a.re  false  vertebrae,  varying- 

in    number    from    thirteen    to    twenty.  ,  -In    form,    they  are    the 

most  rudimentary  of  all  the  vertebral  segments;    their  centra  are 


THE    EIBS. 


33 


oblong,  mostly  constricted  in  the  centre,  and  expanded  where 
they  articulate  with  one  another  :  the  four  or  five  anterior  ones 
are  slightly  flattened  above,  hollowed  longitudinally  below,  and 
they  possess  generally  inconaplete  arches  and  imperfectly-developed 
processes.  The  remaining  segments  consist  merely  of  centra, 
which  diminish  in  size  posteriorly.  There  is,  therefore,  no  complete 
neural  canal  in  the  caudal  region,  only  the  first  two  or  three 
Vertebrae  being  sometimes  found  with  their  neural  arches  complete. 


THE    THORAX. 

The  dorsal  vertebrae  superiorly,  the  ribs  and  their  cartilages 
laterally,  and  the  sternum  or  breast-bone  inferiorly,  form  the 
skeleton  of  a  large  cavity  called  the  Thorax. 


THE  EIBS. 
(Pl.  I.  T.  T.) 

In  the  horse  the  ribs  usually  number  eighteen  on  each  side. 
They  extend  in  a  series  of  arches  of  varying  curvature  from  the 
dorsal  vertebrse  above,  towards  the  sternum  and  sides  of  the 
abdomen  below.  Their  shape,  in  a  great  measure,  determines 
the  conformation  of  the  thorax  ;  they  protect  its  contents,  and 
materially  aid  in  its  contraction  and  expansion. 

To  the  distal  end  of  each  rib  an  elongated  piece  of  cartilage  is 
attached,  and  eight  of  these  connect  the  eight  anterior,  termed 
sternal  or  true  ribs,  with  the  sternum  ;  the  ten  posterior  ribs, 
having  only  an  indirect  sternal  attachment  are  known  as  asternal 
or  false  ribs.  The  ribs  pass  first  outwards  and  backwards,  and 
then  in  an  arched  direction  downwards,  their  cartilages  inclining 
inwards  and  forwards.  They  gradually  lengthen  from  the  first  to 
the  ninth,  after  which  they  progressively  shorten ;  their  curvature 
increases  from  the  first,  which  is  nearly  straight,  to  the  last,  which 
forms  a  large  segment  of  a  comparatively  small  circle.  The 
greatest  breadth  is  attained  in  the  fifth,  sixth,  seventh,  and  eighth, 
which,  in  their  middle  portions,  exhibit  the  more  especial  characters 
of  flat  bones. 

Each  rib  presents  for  consideration  superior  and  inferior 
extremities,  and  a  shaft  or  body  having  anterior  and  posterior 
borders  and  external  and  internal  surfaces. 


34  OSTEOLOGY. 

The  superior  or  proximal  extremity  consists  of  a  head,  a  neck, 
and  a  tubercle.  The  head,  which  rests  in  a  cavity  in  the  verte- 
brae, is  separated  by  a  vertical  furrow,  in  which  the  interarticular 
ligament  is  attached,  into  two  convex  articular  surfaces — one  of 
which  is  directed  forwards  and  inwards,  and  the  other  backwards 
and  inwards.  The  neck  is  the  constricted  portion  supporting  the 
head  ;  it  is  strong  and  roughened  for  ligamentous  attachment, 
and  has  a  groove  for  the  intercostal  nerves  and  blood-vessels 
running  across  it  in  front.  The  tubercle  is  the  prominent  emi- 
nence at  the  posterior  part  of  the  neck  ;  it  has  a  flat,  smooth 
facet,  which  articulates  posteriorly  with  the  transverse  process  of 
a  -vertebra.  External  to  the  tubercle  is  another  eminence,  the 
angle,  where  the  rib  is  suddenly  bent  downwards ;  the  distance 
between  the  angle  and  the  head  of  the  rib  gradually  increases 
from  the  third  to  the  last,  the  first  two  scarcely  possessing 
angles.  In  the  third  and  fourth  ribs  the  angles  and  the  tuber- 
cles are  from  one  to  two  inches  apart,  which  distance  increased!, 
in  a  well-formed  horse,  to  nearly  five  inches  in  the  last.  In  horses 
possessing  well-rounded  chests  the  costal  angles  are  plainly  marked 
and  separated  from  the  vertebrae,  so  as  to  form  large  costal  grooves 
for  the  dorsal  muscles  ;  in  flat-sided  animals  they  are  indistinct 
and  close  to  the  spinal  column,  the  grooves  being  consequently 
narrower. 

The  inferior  or  distal  extremity  is  expanded  and  constructed 
of  more  elastic  bone  than  the  proximal  extremity  ;  it  is  quit*; 
porous,  and  joined  firmly  to  its  cartilage.  The  anterior  ho^-der 
is  rough,  and  excavated  along  its  upper  third  to  give  attachment 
to  the  intercostal  muscles.  The  posterior  border  is  grooved  along 
its  upper  third  for  the  intercostal  muscles,  nerves,  and  blood- 
vessels; in  both  borders  the  distal  portion  is  thinner  in  the  anterior 
than  in  the  posterior  ribs.  The  external  surface  is  convex  in 
every  direction ;  between  the  head  and  the  angle  it  is  roughened 
for  muscular  attachment,  and  below  this  point  smooth,  excepting 
in  a  few  places,  the  chief  of  which,  a  short  distance  below  the 
angle,  give  attachment  to  muscles.  The  internal  surface,  concave 
from  above  downwards,  and  convex  from  side  to  side,  is  smooth, 
ajad  ror  the  greater  part  covered  by  the  pleura,  the  membrane 
lining  the  thorax. 

With  the  exception  of  the  last,  and  sometimes  the  last  two  on 
each  side,  each  rib  has  its  cartilage.  These  cartilages,  which 
contain  a  large  quantity  of  earthy  or  bony  material,  pass  obliquely 


STERNUM.  35 

forwards  and  inwards  ;  they  diminish  in  thickness  from  before 
laackwards,  but  increase  in  length  to  ^he  eleventh  or  twelfth, 
■after  which  they  again  grow  shorter.  Those  attached  to  the 
true  ribs  are  smallest  at  their  proximal  ends,  becoming  expanded 
before  they  articulate  with  the  sternum  ;  those  of  the  false  ribs 
are  largest  at  their  proximal  ends,  and,  gradually  tapering  to  fine 
points  below,  they  pass  forwards  and  downwards,  so  that,  having 
no  inferior  articulations,  each  is  overlapped  by  the  succeeding 
one. 

The  special  ribs  are  the  two  first  and  the  last  four  or  five. 
The  first  is  shorter  and  straighter  than  the  others,  with  rough 
surfaces,  rounded  borders,  and  no  well-defined  posterior  groove  ; 
its  head  is  irregular  in  shape,  and  exceeded  in  size  by  the  tubercle, 
and  its  distal  end  is  flattened  and  expanded  laterally,  joining 
the  short  thick  cartilage,  which  contains  much  ossific  matter. 
The  second  possesses  the  above-named  characters  of  the  first  in  a 
less  degree.  The  last  four  or  five  are  slender  ;  the  articular 
surfaces  of  their  tubercles  and  the  posterior  divisions  of  their 
beads  are  usually  continuous  ;  their  curvature  is  great ;  they  are 
broadest  immediately  behind  the  tubercle,  and  their  cartilages 
are  remarkably  slender  and  elongated. 

Each  true  rib  has  four  articular  surfaces,  two  on  the  head, 
■one  on  the  tubercle,  and  one  at  the  distal  end. 


STERNUM. 

The  sternum  or  breast-bone,  a  comparatively  small  and  short 
bone  in-  the  horse,  is  single  in  the  adult,  and  placed  in  the 
inferior  longitudinal  line  of  the  body  at  the  antero-inferior  part 
of  the  thorax.  The  anterior  portion  somewhat  resembles  the 
keel  and  cut- water  of  a  boat ;  it  is  elongated  and  concave  above, 
convex  below,  with  its  anterior  part  flattened  laterally,  and  its 
posterior  part  flattened  above  and  below.  It  is  constructed  of 
six,  rarely  seven,  irregularly-formed  segments  or  sternebrcB, 
united  by  cartilage  in  the  young  animal,  and  by  partial  ossifica- 
•^os  in  the  adult ;  complete  ossification  seldom  or  never  takes 
place  in  this  bone.  Its  anterior  end  is  surmounted  by  the  carini- 
form-  cartilage,  and  its  posterior  extremity  prolonged  by  the 
«nsiform  or  xiphoid  cartilage. 

Its  superior  surface  is  triangular  in  outline  and  concave,  the 
superior    sternal    ligaments    traversing    its    lateral   borders.       Its 


36  OSTEOLOGY. 

inferior  -surface  is  narrow  anteriorly  and  convex,  the  centre  pre- 
senting a  prominent  ridge  coated  with  cartilage,  materially 
increasing  the  lateral  surfaces,  which  give  origin  to  the  pectoral 
muscles ;  the  sides  are  flat  and  irregular,  and  present  between 
the  segments  depressions,  in  which  the  cartilages  of  the  true  ribs 
articulate,  another  depression  being  entirely  formed  in  the  first, 
apd  an  eighth  in  the  last  segment.  These  depressions  are 
oval  in  shape,  and  are  nearer  to  each  other  as  they  proceed 
backwards. 

The  Carinifor^iL  or  keelshxiped  cartilage  presents  a  convex 
border  looking  forwards  and  upwards,  and  elevated  so  as  to  sur- 
mount the  articular  depressions  for  the  first  pair  of  costal 
cartilages,  to  which  it  is  attached  by  ligaments ;  laterally  it  is 
flattened  to  increase  the  surface  for  muscular  attachment ;  and 
its  inferior  border,  prolonged  over  the  first  segments  of  the  sternum, 
terminates  in  the  cartilaginous  ridge.  The  prominent  convexity 
which  this  cartilage  forms  may  often  be  plainly  distinguished  in 
the  living  animal. 

The  Xiphoid  or  Ensiform  cartilage  is  somewhat  heart-shaped, 
the  apex  being  directed  downwards  an^  backwards.  Its  superior 
surface,  broad  and  cup-shaped,  occupies  a  space  bounded  by  the 
cartilages  of  the  false  ribs,  and  supports  -part  of  the  abdominal 
viscera.  Its  inferior  surface  is  convex,  and  roughened  for  muscular 
attachment,  and  its  free  borders  are  thin.  It  affords  attachment 
for  muscles,  and  for  a  fibrous  cord  called  the  linea  alba. 

The  bony  framework  of  the  thoracic  cavity  bears  some  resem- 
blance to  a  truncated  cone,  with  its  apex  or  anterior  extremity 
compressed  laterally.  The  anterior  aperture  is  a  triangular  space, 
having  its  apex  directed  downwards  and  slightly  forwards,  formed 
by  the  sternum,  the  first  pair  of  ribs,  and  the  first  dorsal  vertebra; 
it  gives  passage  to  the  oesophagus,  trachea,  and  various  important 
nerves  and  blood-vessels.  The  base  or  posterior  aperture  is  oval 
in  outline,  and  slopes  obliquely  downwards  and  forwards  from 
the  vertebrae ;  it  is  formed  by  the  last  dorsal  vertebra,  the  last 
pair  of  ribs,  the  cartilages  of  the  false  ribs,  and  the  Xiphoid 
cartilage,  and  its  boundary  gives  attax^hment  to  the  diaphragm, 
a  large  muscular  curtain  which,  separates  the  thorax  from  the 
abdomen. 


GENERAL    VIEW    OF    THE    SKULL. 


37 


The  Skull. 


GENERAL     VIEW. 

The  skull,  or  skeletoa  of  the  head,  the  most  anterior  part  of 
the  horse's  skeleton,  articulates  with  the  first  cervical  vertebraj, 
from  which  it  is  suspended  by  its  posterior  extremity,  its  anterior 
extremity    being    free.       Its    position 
varies  with  the  attitude  of  the  animal ; 
but  in   our    descriptions    we   shall 
allude  to  it  as  if  it  were  placed  in  a 
horizontal  position,  as  in  Fig.  12. 

In  the  young  animal  the  skull  is 
composed  of  a  number  of  bones,  all  of 
which,  with  the  exception  of  the  lower 
jaw,  the  teeth,  the  bones  of  the  tongue, 
aud  ossicles  of  the  ear,  become  united 
by  ossification  in  the  adult ;  excluding 
the  teeth  and  the  internal  bones  of  the 
ear,  there  are  thirty-eight  bones  in  the 
skull — six  single  ones,  and  the  rest 
pairs. 

The  skull  is  divisible  into  two  parts 
• — viz.,  the  cranium  or  calvarium,  and 
the  face.  The  former  is  a  cavity  situ- 
ated in  the  supero-posterior  region  of 
the  skull,  and  continuous  with  the 
spinal  canal;  it  contains  the  brain  and 
its  appendages,  and  in  the  horse  is 
comparatively  a  small  cavity,  occupying 
about  one-fifth  of  the  skull.  The  re- 
maining bones  of  the  skull  collectively 
form  the  face,  hence  the  whole  struc- 
ture is  composed  of  cranial  and  facial 
bones.  We  shall  first  end6avour  to 
give  a  general  idea  of  the  articulated 
skull,  and  afterwards  describe  separately  the  bones 
pose  it. 

The  bones  of  the  head  are  in  early  life  united  to  each  other 
by  means  of  sutures,  or  interposed  layers  of  fibrous  material,  and 
after  union  by  ossification,  a  well-marked   line  usually  indicates 


Fig.  10. 
Skull  of  the  Horse  seeu  from  above 
I.  Occipital  bone  ;  II.  Parietal  bone  • 
III.  Squamosal  bone ;  IV.  Frontal 
bone  ;  V.  Nasal  bone  ;  VI.  Lachrymal 
bone  ;  VII.  Malar  bone  ;  VIII.  Sup- 
erior Maxilla ;  IX.  Premaxjlla.  a. 
Occipital  crest ;  6,  Parietal  cr«st ;  c. 
Orbital  process;  d,  Supraorbital  for- 
amen. 


'hich 


38  OSTEOLOGY. 

the  position  of  the  late  suture.  One  of  the  principal  sutures  of 
the  skull  is  the  longitudinal,  which  extends  in  the  median  line 
from  the  poll  to  the  nasal  peak,  and  marks  the  division  of  the 
^kull  into  two  lateral  halves. 

In  shape  the  skull  resembles  a  quadrangular  pyramid,  and 
contains  various  cavities  or  chambers.  Supposing  it  to  be  placed 
in  the  horizontal  position  resting  on  the  lower  jaw,  we  can  more 
easily  give  a  general  description  of  the  most  important  external 
features  if  we  divide  it  into  the  following  regions  : — Superior, 
Inferior,  Lateral,  Anterior,  and  Posterior. 

The  Superior  region  is  a  surface  formed  by  three  pairs  of  bones, 
'Called  the  parietal,  frontal,  and  nasal,  each  bone  being  joined  to 
its  fellow  by  a  part  of  the  longitudinal  suture.  The  parietal 
bones  are  the  hindermost  of  the  three,  and  are  convex,  forming 
part  of  the  roof  of  the  cranium  or  brain  cavity,  while  the  frontal 
(or  middle  pair  are  flatter,  and  very  broad  above  the  level  of 
iibe  orbits,  the  region  of  the  forehead.  The  nasal  bones  together 
form  a  semi-cylinder,  and  gradually  diminish  in  breadth  anteriorly, 
finally  forming  the  projecting  nasal  peak.  The  prominent  trans- 
verse ridge  bounding  this  region  posteriorly  is  the  occipital  crest. 

The  Inferior  region  presents  a  very  irregular  surface,  bounded 
l)elow  by  the  inferior  maxilla  or  lower  jaw,  a  bone  whose  two 
segments  are  firmly  united  anteriorly,  but  diverge  backwards 
somewhat  in  the  form  of  a  letter  V,  each  terminating  superiorly 
in  a  convex  articular  surface,  the  maxillary  condyle,  before  which 
is  the  prominent  coronoid  process,  the  lever  of  the  lower  jaw. 
The  diverging  parts  or  rami  of  the  jaw  include  a  space,  appro- 
priately called  the  maxillary^  space.  We  find  in  the  united  or 
anterior  portion  of  this  bone  the  inferior  incisor  and,  in  the  male, 
the  canine  teeth,  and  in  the  rami  the  inferior  molars  or  grinders ; 
the  space  between  the  molar  and  front  teeth  is  called  the 
diasteraa  or  interdental  space,  and  is  always  large  in  herbivorous 
animals. 

If  we  remove  the  inferior  maxilla,  we  notice  the  following 
objects  : — Anteriorly  the  premaxilla,  bearing  the  upper  incisor 
and  partly  the  canine  teeth,  and  just  behind  the  incisors,  in  the 
median  line,  a  small  round  aperture,  the  foramen  incisivum,  while 
the  interdental  space  and  molar  teeth  are  similar  to  those  in  the 
lower  jaw.  The  flattened  surface  extending  from  the  incisors 
backwards  between  the  molars  is  the  bony  palate,  formed  chiefly 
;by  the  superior  maxilla,  and  bounded  posteriorly  by  the  palatine . 


GENERAL    VIEW    OF    THE    SKULL, 


39 


urch,  which  is  semi-elliptical  in  form,  aud  marks  the  entrance  to 
a  large  cavity  above  called  the  nasal  chartxber  ;  this  cavity  is  in 
the  fresh  state,  divided  into  right  and  left  compartments  or  fossm 
by  a  cartilaginous  septum. 

Between  the  posterior  molars  and  the  palatine  arch  are  the 
two  palatine  foramina.  Behind,  and 
bounded  by  the  palatine  arch,  are  the 
entrances  to  the  nasal  chamber,  right 
and  left,  called  the  posterior  nares, 
and  the  slender  median  bone  stretch- 
ing from  behind  forwards  in  the  cavit}' 
is  the  vomer  ;  it  indicates  the  division 
of  the  chamber  into  right  and  left 
fossae.  Continuous  with  the  vomer 
we  find  an  irregular  column  of  bone 
reaching  to  the  back  of  the  skull ; 
this  column  consists  of  three  pieces, 
the  pre-sphenoid  anteriorly,  then  the 
basi-sphenoid,  and  lastly  the  basi- 
occipital  bone.  These  bones  are 
respectively  parts  of  the  sphenoid  and 
occipital  bones,  and  they,  together 
with  the  vomer,  are  regarded  as  the 
centra  of  the  cranial  vertehrce ;  and 
the  ossified  suture  between  the  last 
two  bones  is  usually  marked  by  a 
roughened  ridge. 

On  the  posterior  edges  of  the  pala- 
tine arch  are  two  small  sharp  projec- 
tions, the  ends  of  the  pterygoid  bones, 
and  behind  them  the  rough  palatine 
ridges,  the  posterior  edges  of  which 
are  formed  by  the  pterygoid  processes 
of  the  sphenoid  bone  ;  outside  the 
base  of  each  of  these  processes  we 
have  the  posterior  aperture  of  the 
suh sphenoidal  or  pterygoid  foramen,  which  gives  passage  ta 
an  important  artery.  There  are  two  large,  rounded,  and  may  be 
roughened  prominences,  the  alveolar  tuberosities,  immediately 
behind  the  last  molar  teeth,  and  between  them  and  the  palatini 
ridges   and  pterygoid   bones   are  the   smooth   staphyline  grooves. 


Fig  11 
Inferior  aspect  of  Hoises  skull, 
the  mandible  being  removed.  Above 
the  line  A  is  the  posterior  region  or 
base,  between  A  and  B  the  middle, 
aud  below  B  the  anterior  or  nasal 
region,  a.  Occipital  condyle ;  b,  Fora- 
men magnum  ;  c,  Styloid  process  ; 
d.  Temporal  articular  surface  ;  e,  Basi- 
occipital,  and/,  Basi-sphenoid  bones  ; 
g,  Petrosal  bone  ;  h,  Ali  -  sphenoid 
bone  ;  i,  Temporal  bone  ;  fc.  Condyloid 
foramen  ;  fc'  Condyloid  notch ;  I,  Fora- 
men lacerum  basis  cranii ;  m.  Ptery- 
goid foramen  ;  n.  Palatine  suture  ; 
o,  Palatine  foramen  ;  p,  Molar  teeth  ; 
q,  Incisive  opening  ;  r.  Foramen 
incisivum. 


40  OSTEOLOGY. 

Outside  the  palatine  ridges  there  are  two  very  large  spaces,  the 
orbito-temporal  cavities  ;  each  of  these  is  bounded  externally  by 
the  zygomatic  arch,  a  horizontal  process  composed  of  parts  of 
the  malar  and  squamosal  bones,  anteriorly  by  the  alveolar 
tuberosity,  posteriorly  by  the  articular  surface  of  the  squamosal 
bone,  with  which  the  inferior  maxilla  articulates,  and  internally 
by  the  sphenoid  and  palatine  bones.  The  cavities  open  each 
by  two  large  apertures  on  the  lateral  aspect  of  the  skull ;  the 
posterior  portion  being  called  the  temporal,  the  anterior  the 
orbital  fossa.  In  the  higher  orders  of  mammals,  the  bimana 
and  quadruniana,  these  two  fossae  are  completely  separated  from 
eacli  other  by  a  bony  process  or  plate.  The  articular  surface 
of  the  squamosal  bone,  above  named,  terminates  posteriorly  in 
a  projection  called  the  anterior  mastoid  process,  behind  and 
internal  to  which  is  a  very  irregularly-shaped  bone,  the  petrosal, 
characterised  by  the  external  auditory  meatus,  a  bony  tube 
which  is  directed  outwards  and  upwards,  and  also  by  a  slender 
spike,  projecting  downwards  and  forwards,  called  the  styloid 
process ;  the  petrosal  bone  contains  the  internal  mechanism  of  the 
ear,  and  also  gives  attachment  to  the  cornu  of  the  os  hyoides,  or 
'Jbone  of  the  tongue. 

Between  the  petrosal  and  basi-occipital  bones  we  have  a  large 
and  very  irregularly-shaped  aperture,  leading  into  the  cranial 
cavity  ;  this  is  the  foramen  lacerum  basis  cranii,  and  it  gives 
passage  to  some  important  nerves  and  vessels  ;  anteriorly,  the 
foramen  lacerum  is  bounded  by  a  flattened  plate,  the  part  of 
the  sphenoid  bone  called  the  wing  or  ali-sphenoid ;  and  on  the 
internal  part  of  the  edge  of  the  wing  is  the  carotid  notch,  through 
which  the  endocarotid  artery  enters  the  cranium.  Posterior  to 
the  petrosal  bones,  two  large  processes  pomt  downwards ;  these 
are  the  occipital  styloid  processes,  which  must  be  distinguished 
from  the  small  petrosal  ones  before  alluded  to.  Still  farther  back 
we  have  the  occipital  condyles,  by  which  the  head  articulates 
with  the  atlas  ;  a  deep  notch,  the  stylo-condyloid  notch,  separates 
each  condyle  from  the  styloid  process,  and  at  the  bottom  of  the 
notch  on  its  internal  aspect  is  the  condyloid  foramen,  leading 
into  the  cranium. 

The  Lateral  surfaces  exhibit  inferiorly  the  external  face  of  the 
rami  of  the  inferior  maxilla,  and  antero-superiorly  a  triangulai' 
space,  formed  chiefly  by  the  superior  maxilla,  more  or  less  convex 
but  sometimes  hollowed  in  old  animals,  and  presenting  the  infra- 


GENERAL  VIEW  OF  THE  SKULL.  41 

orbital  foramen  in  its  centre.  The  zygomatic  arch  presents 
externally  a  well-marked  edge  or  line,  which  is  continued 
anteriorly  by  a  ridge,  called  the  maxillary  spine.  A  process 
thrown  outwards  and  downwards  by  the  frontal  bone  articulates 
with  the  zygomatic  arch  about  its  middle  ;  it  is  called  the  frontal 
or  external  orbital  arch,  and  it  indicates  the  division  of  the  cavity 
within  into  orbital  and  temporal  fossag. 

The  orbital  fossa  is  a  conical  cavity,  the  oval  entrance  of  which 
is  circumscribed  by  the  frontal,  the  lachrymal,  malar,  and  part  of 
the  zygomatic  process  of  the  squamosal  bone  ;  in  addition  to 
these,  the  cavity  is  formed  by  the  superior  maxilla,  the  palatine, 
-and  the  anterior  wing  of  the  sphenoid,  called  the  orbito-sphenoid 


Fig.  12. 

Lateral  aspect  of  a  Horse's  skull.  1,  Occipital  bone  ;  2,  Parieta 
bone  ;  3,  Frontal  bone  ;  9,  Nasal  bone  ;  11,  Nasal  peak  :  10,  Premaxilla 
8,  Superior  maxilla  ;  6,  Laclirjmal  bone  ;  7,  Malar  bone  ;  5,  Zygomatic 
process  of  the  squamosal  bone ;  4,  Petrosal  bone— c,  its  external 
meatus  ;  12,  Inferior  maxilla  ;  H.  Coronoid  process  of  inferior  maxilla 
occupying  the  temporal  fossa  ;  K,  Temporo-maxillary  articulation  ; 
I,  Molar  teeth. 

l)one.  Deep  in  the  fossa  anteriorly  is  a  depression,  the  maxillary 
hiatus,  which  leads  to  the  palatine,  spheno-palatine,  and  superior 
dental  foramina,  and  posteriorly  another  depression,  the  orbital 
hiatus,  containing  the  optic,  pathetic,  lacerated,  and  round 
foramina.  This  cavity  contains  the  eye,  the  muscles  by  which  it 
is  moved,  the  lachrymal  gland,  and  all  accessories  to  the  organ, 
together  with  a  large  quantity  of  adipose  tissue  or  fat. 

The  temporal  fossa  is  incompletely  separated  from  the  orbital 
by  the  orbital  arch,  complete  separation  of  these  cavities  by  a 
wall  of  bone  being  found  only  in  man  and  the  quadrumana.  It 
is  oval  in   shape,   situated  in   an   oblique   direction,  from   within 


42  OSTEOLOGr. 

outwards,  and  is  bounded  internally  by  a  rough  line,  the  parietal 
crest,  and  externally  by  the  superior  edge  of  the  zygomatic 
process.  It  lodges  the  temporal  muscle  and  the  lever  process, 
of  the  lower  jaw,  and  contains  many  foramina,  which  lead  to  a.. 
cavity  between  the  bones  called  the  parieto-temporal  conduit. 

The  Posterior  part  or  base  of  the  skull  presents  superiorly  the 
roughened  occipital  crest  continued  downwards  by  the  sharp 
mastoid  ridges,  which  again  are  continuous  with  ridges  on  the 
squamosal  bones,  and  so  with  the  upper  edges  of  the  zygomatic 
arches.  Below  the  crest  is  a  broad,  slightly-roughened  surface, 
and  below  that,  in  the  median  line,  is  the  neural  canal  of  the 
occipital  bone,  called  the  foramen  magnum,  bounded  laterally 
by  the  condyles,  which  again  are  flanked  by  the  styloid  processes, 
and  separated  from  them  by  the  stylo-condyloid  notches. 

The  Anterior  part  or  apex,  formed  by  the  premaxilla  and  body 
of  the  inferior  maxilla,  contains  the  incisor  teeth,  and  is  more  or 
less  rounded  in  profile,  according  to  the  age  of  the  animal.  In 
front,  it  is  surmounted  by  the  external  opening  of  the  nasal 
cavities  ;  this  opening,  included  between  the  premaxilla  and  the 
nasal  spine,  is  divided,  in  the  fresh  subject,  into  two  orifices,  the 
anterior  nares. 

CAVITIES    IN    THE    SKULL. 

The  skull  contains  internally  the  cranial  cavity,  the  nasal 
fossce  or  chambers,  and  the  sinuses,  which  are  appendages  to  the 
latter. 

CRANIUM. 

The  Cranium  is  an  extremely  irregular  ovoid  cavity,  the  walls 
of  which  are  formed,  by  the  frontal,  parietal,  occipital,  temporal,, 
sphenoid,  and  ethmoid  bones.  For  the  purpose  of  description, 
it  may  be  regarded  as  being  divisible  into  a  roof,  a  floor  or 
inferior  surface,  two  lateral  surfaces,  and  two  ends. 

The  Roof  presents,  towards  its  posterior  third,  in  the  median 
line,  the  parietal  protuberance,  or  ossific  tentorium,  which,  with 
the  two  lateral  ridges  springing  from  it,  and  which  may  be 
regarded  as  a  part  of  it,  assists  in  dividing  the  cranial  cavity  into 
two  compartments — a  posterior  one,  for  the  cerebellum,  and  an 
anterior,  considerably  larger,  for  the  cerebrum.  Along  the 
median  line,  from  this  eminence  to  the  front  of  the  roof  runs 
a  groove,  the  roughened  elevated  borders  of  which  form  a  rudi- 


CRANIUM.  43 

mentary  crest,  to  support  the  membrane  which  divides  the 
compartment  into  two  lateral  sections,  one  for  each  hemisphere 
of  the  cerebrum.  Folds  of  membrane  attached  to  the  protuber- 
ance, and  lateral  ridges,  also  render  the  transverse  partitioning 
of  the  cavity  more  perfect. 

The  Lateral  surfaces  are  concave,  and.  like  the  roof,  marked 
with  numerous  smooth  grooves  and  impressions.  They  assist  m 
the  division  into  cerebral  and  cerebellar  compartments  by  means 
of  the  parieto-temporal  ridges,  which  are  prolonged  obliquely  as 
far  as  the  sphenoid  bone,  the  first  portion  being  formed  by  the 
occipital  and  internal  face  of  the  petrosal,  and  the  second  by  the 
squamosal  bone. 

The  Floor  or  inferior  surface  is  very  irregular,  and  presents, 
from   behind   forwards,  in  the  median  line,  the   bones   which 


Fig.  13. 
Longitudinal  section  of  a  Horse's  skuU.  1,  Supraoccipital  bone  and 
crest ;  2,  Parietal  bone  :  3,  Frontal  boue  ;  4,  Frontal  sinuc:  5,  Nasal  bone  ; 
6,  Superior  turbinal  :  12.  Inferior  turbinal :  14.  Superior  maxiUa,  and  13. 
its  palatine  plate  :  15.  Premaiilla  :  11.  Palatine  bone  :  7.  Ethmoid  bone  and 
volutes  :  8.  Basi  and  pre-sphenoid  bones  :  9.  Basi-occipital  bone  :  10. 
Petrosal  bone.     The  craniii:ai  is  the  cavity  under  1  and  2. 

represent  the  three  posterior  centra  of  the  cranial  vertebrae — viz.. 
the  basi-occipital,  basi-sphenoid.  and  pre-sphenoid  bones ;  and 
laterally  we  find  the  foramina  lacera  basis  cranii,  the  remaining 
portion  of  the  floor  being  formed  by  the  ali-sphenoid  and  orbito- 
sphenoid  bones  the  former  presenting  on  each  side  of  the  centrum 
two  grooves  running  forwards,  and  terminating  in  foramina.  On 
the  pre-sphenoid  is  a  transverse  slit,  the  cptlc  hiatus,  and  the 
raised  ledge  posterior  to  it  is  the  olivary  process,  behind  which 
we  find  the  sella  turcica,  a  depression  in  the  basi-sphenoid  bone. 
Laterally,  the  bony  floor  coalesces  with  the  walls  so  as  to  form 
deep  ovoid  cavities,  which  receive  the  mastoid  or  great  lobes  of 
the  cerebrum. 

The  Posterior  end  contains  the  foramen  magnum,  by  means  of 
which  the  cavity  communicates  with  the  spinal  canal. 


44  OSTEOLOGY. 

The  Anterior  end  presents  the  perpendicular  crista  galli  process, 
in  the  median  line,  on  each  side  of  which  are  the  ethmoidal  fossae, 
the  cribriform  lamellae  of  the  ethmoid  bone  forming  their  anterior 
boundary. 

NASAL    FOSS^. 

The  Nasal  fossae  are  two  cavities,  separated  in  the  fresh  state 
by  a  cartilaginous  septum,  which  extends  from  the  ethmoid  bone 
to  the  anterior  nares.  The  framework  of  these  fossae  is  formed 
by  the  nasal,  the  superior  maxillary,  the  frontal,  and  the  palatine 
bones,  the  whole  forming  a  spacious  irregular  tube,  bounded 
posteriorly  by  the  ethmoid  bone,  two  turbinated  bones  being 
situated  in  each  fossa.  The  vomer  in  the  median  line,  gives 
attachment  below  to  the  cartilaginous  septum. 


These  are  winding  cavities  in  the  bones  of  the  face.  They 
communicate  freely  with  each  other  and  with  the  nasal  fossae, 
of  which  they  may  be  regarded  as  prolongations.  Ordinarily, 
they  number  four  on  each  side — viz.,  the  frontal,  the  maxillary, 
the  sphenoidal,  and  the  ethmoidal. 

The  Frontal  sinus  is  situated  inside  the  inner  plate  of  the 
orbital  fossa,  its  extremely  irregular  walls  being  formed  by  the 
frontal,  nasal,  lachrymal,  ethmoid,  and  superior  turbinated  bones. 
It  communicates  with  the  maxillary  sinus  belov/  by  means  of  a 
large  opening  through  the  delicate  bony  partition  between  them. 
A  thick  vertical  plate,  often  placed  more  to  one  side  than  the 
other,  and  always  imperforate,  separates  this  sinus  from  that  of 
the  opposite  side. 

The  Mobxillary  sinus,  formed  below,  and  before  the  orbit  by 
the  superior  maxillary,  malar,  ethmoid,  lachrymal,  and  inferior 
turbinated  bones  is  the  largest  of  the  sinuses.  A  ridge  which 
contains  the  superior  dental  canal,  divides  it  into  two  chief 
compartments — an  internal,  which  is  a  shallow  recess  continuous 
with  the  sphenoidal,  and  communicating  with  the  ethmoidal  sinus, 
and  an  external,  divided  into  two  chambers  by  a  transverse  plate, 
which  frequently  (according  to  some  authorities,  always)  remains 
perfect  through  life,  and  completely  isolates,  the  anterior  chamber. 
The  posterior  of  these  chambers  is  prolonged  backwards  to  the 
alveolar  tuberosity,  and  has  the  roots  of  the  two  last  molar  teeth 


OCCIPITAL    BONE.  4,5 

jutting  into  it.  The  anterior  chamber  is  subdivided  into  twi> 
parts,  the  internal  of  which  is  prolonged  into  the  inferior  tnrbinal 
bone,  the  external,  which  is  the  smallest,  having  an  elevation  on 
its  floor  caused  by  the  root  of  the  fourth  molar  tooth. 

The  Sphenoidal  sinus  is  a  small  irregular  cavity  formed  in  the 
sphenoid,  ethmoid,  and  palatine  bones.  It  is  subdivided  by 
inconiplete  partitions  into  several  compartments,  especially  into 
an  anterior  included  between  the  plates  of  the  palatine,  and  a 
well-marked  posterior  one,  excavated  in  the  pre-sphenoid  bone  ; 
the  latter  is  separated  from  its  fellow  on  the  opposite  side  by  a 
perforated  lamella. 

The  Ethmoidal  sinus,  the  smallest  of  these  cavities,-  is  a  space 
included  in  the  volute  of  the  ethmoid  bone.  It  communicates 
by  a  small  opening  with  the  maxillary  sinus. 

The  sinuses  which  contain  air,  and  are  larger  in  the  adult 
than  in  the  young  animal,  are  partially  divided  by  imperfect 
septa,  which  run  across  their  interior  ;  in  the  fresh  state  they 
are  lined  with  mucous  membrane. 


Separate  Bones  of  the  Skull. 

cranial  bones. 

The  bones  of  the  Cranium  which  we  now  proceed  to  describe 
separately,  are  the  occipital,  sphenoid,  ethmoid,  and  Wormian 
bones,  which  are  single,  and  the  parietal,  frontal,  and  temporal 
bones,  arranged  in  pairs ;  the  temporal  bone  is,  in  the  horse, 
divided  into  two  parts,  the  squamosal  and  petrosal  bones. 

occipital    BONE. 

(Fig.  10.  I. ;  12.  1.) 

This  bone  occupies  the  posterior  part  of  the  skull,  and  is  in 
the  young  animal  divisible  at  first  into  four  pieces,  and  afterwards 
into  two,  which  finally  unite  to  form  one  bone  ;  it  is  very 
irregular,  and  presents  an  external  and  an  internal  surface  and 
borders. 

The  external  surface  may  be  thus  described.  The  upper  or 
supraoccipital  portion  being  very  much  exposed,  is  thick  and  strong; 
it  terminates  superiorly  in  a  prominent  crest,  the  crest  of  the 
occiput,  which  is  convex  anteriorly,  and   gives  attachment  to  the 


46  OSTEOLOGY. 

complexus  major  muscle,  and  below  it  at  the  back  is  the  occipital 
tuberosity,  on  each  side  of  which  there  is  a  roughened  depression 
for  the  attachment  of  the  cordiform  part  of  the  ligamentum  nuchse. 
The  occipital  or  mastoid  ridge,  continuous  with  the  squamosal 
bone,  descends  from  the  crest  on  each  side,  and  gives  attachment 
to  various  muscles.  The  inferior  or  suboccipital  portion  presents 
a  little  below  the  tuberosity,  a  large,  oval  hole,  the  foramen 
magnum,  through  which  pass  the  spinal  cord,  the  spinal  acces- 
sory nerves,  and  the  basilar  artery ;  the  sides  of  this  fora- 
men, the  transverse  diameter  of  which  is  the  larger,  are  slightly 
roughened  for  the  attachment  of  the  long  odontoid  ligaments, 
and  on  each  side  is  a  large  rounded  prominence,  the  condyle, 
which  articulates  with  the  atlas.  A  large  process,  the 
basilar  process  (basi-occipital  bone),  passes  forwards  from  the 
lower  part  of  the  condyles,  and  forms  the  floor  of  the  foramen, 
magnum,  being  flattened  and  slightly  hollowed  above,  but  rounded 
below,  where  it  gives  attachment  to  the  rectus  capitis  anticus 
major  and  minor  muscles;  it  articulates  with  the  sphenoid  bone  in 
front,  and  has  a  fissure,  the  basilar  fissure,  running  along  its  under 
surface,  terminating  posteriorly  in  the  foramen  magnum.  Two 
flattened  styloid  processes  extend  downwards  from  the  sides,  of 
the  bone,  and  give  attachment  to  the  obliquus  capitis  anticus, 
stylo-maxillaris,  and  stylo-hyoideus  muscles  ;  and  between  each 
of  these  processes  and  the  condyle  is  a  deep  notch,  the  condyloid 
or  stylo-condyloid  notch,  at  the  bottom  of  which  and  just  in 
front  of  the  condyle,  is  the  condyloid  foramen  which  givea 
passage  to  the  twelth  nerve. 

The  internal  or  cerebral  surface  has,  in  the  supraoccipital 
portion,  a  vaulted  concavity  termed  the  occipital  cupola,  which 
covers  the  cerebellum  ;  while  the  superior  surface  of  the  basilar 
process  presents  a  pit,  the  basilar  fossa,  in  the  anterior  part  of 
which  the  pons  varolii  lies,  and  in  the  posterior  part  the  medulla 
oblongata.  The  small  foramina  which  enter  the  basilar  process 
from  within  the  foramen  magnum  are  for  the  passage  of  nutrient 
blood-vessels.  The  superior  border  is  serrated,  and  articulates 
with  the  parietal  and  the  lateral  borders  with  the  petrosal  bones. 
The  occipital  bone  resembles  a  vertebra  more  than  any  other 
of  the  so-called  cranial  vertebrae ;  in  the  young  state  it  separates 
into  an  inferior  or  basi-occipital  part,  representing  the  centrum ; 
two  lateral  exoccipitals,  representing  the  pedicles,  laminae,  &c. ; 
and    above,    the    supraoccipital     portion,    corresponding    to    the. 


PARIETAL    BONE.  47 

tubercle  of  the  neural  spine.  The  occipital  bone  articulates  with 
eight  bones — the  parietals,  squamosals,  petrosals,  sphenoid,  and 
the  atlas. 

PARIETAL    BONE. 
(Fig.  10.  n.  J  12.  2.) 

These  bones  are  situated  at  the  superior  and  lateral  parts  of 
the  cranium,  of  -which  they  form  the  walls  and  part  of  the  roof 
The  parietal  is  a  large  thin  bone,  possessed  of  an  external  and 
^n  internal  surface,  and  four  borders. 

The  external  surface  is  convex  and  smooth.  On  each  side  of 
the  sagittal  suture,  formed  by  the  junction  of  the  two  parietal 
bones,  there  is  a  curved  ridge,  to  which  the  temporalis  muscle  is 
attached  ;  these  ridges  together  form  an  angle,  the  point  of  which 
joins  the  occipital  crest.  The  lateral  parts  of  this  surface  are 
roughened,  to  articulate  with  the  squamosal  bone. 

The  internal  surface  is  concave,  and  marked  by  numerous 
grooves  and  indentations,  which  correspond  with  the  convolutions 
of  the  brain.  A  groove,  termed  the  longitudhval  groove,  and 
generally  formed  by  a  ridge  or  crest,  runs  along  the  junction  of 
the  two  bones,  and  gives  lodgment  to  the  longitudinal  sinus  of 
the  dura  mater  ;  this  crest  terminates  posteriorly  in  a  three-sided 
process,  the  parietal  protuberance  or  ossific  tentorium,  to  which, 
as  well  as  to  the  crest,  is  attached  the  falx  cerebri,  a  part  of  the 
dura  mater  which  contains  the  above-named  sinus.  In  front  of 
this  process  the  longitudinal  groove  ends  in  two  transverse  grooves, 
which  lodge  the  transverse  sinuses  of  the  dura  mater,  and  are 
continued  down  to  the  parieto-temporal  conduit,  a  passage  formed 
between  this  bone  and  the  temporal. 

The  posterior  border  of  this  bone  is  thick  and  denticulated, 
and  articulates  with  the  occipital  ;  the  anterior'  border  is  slightly 
concave  and  strongly  serrated,  articulating  with  the  frontal  bone  ; 
the  internal  border  is  denticulated^  and  united  to  its  fellow  of 
the  opposite  side,  forming  the  saggital  suture ;  the  exte^nial 
border  is  divided  by  a  prominent  angle  into  two  parts,  the 
anterior  one  being  thin,  and  articulating  with  the  squamosal, 
while  the  posterior  is  thicker,  and  articulates  with  the  petrosal 
Ijone,  the  prominent  angle  or  crest  meeting  the  sphenoid  bone. 

Sometimes  the  sagittal  suture  is  interrupted  or  rendered  bifid 
posteriorly  by  the  insertion  of  a  small  bone,  generally  triangular 


48  OSTEOLOGY. 

in  shape,  and  called  the  os  trlquetruTn,  or  Wormian  bone  ;  the 
ossific  tentorium  springs  from  this  bone  when  present.  The 
parietal  bone  articulates  with  its  fellow,  the  occipital,  frontal^ 
squamosal,  petrosal,  and  sphenoid — i.e.,  with  six  bones,  or  with, 
seven  when  the  Wormian  bone  is  present. 


FRONTAL    BONE. 
(Figs.  10.  IV.;  12.  and  13.  3.) 

This  bone  is  situated  at  the  antero-superior  part  of  the  cranium, 
and  the  pair  constitute  the  broad,  flat  part  called  the  forehead  ; 
their  union  in  the  centre  of  the  forehead  forms  the  frontal  suture. 
Each  frontal  bone  is  irregular  in  shape,  flat  externally,  smooth  and 
concave  internally,  and  presents  external  and  internal  surfaces 
and  four  borders. 

The  external  surface  is  somewhat  prominent  above  and  slightly 
depressed  below,  and  has  a  lateral  process,  the  external  orbital, 
which  arches  downwards  and  slightly  backwards,  and  bounds  part 
of  the  orbital  fossa ;  it  articulates  with  the  zygomatic  process  of 
the  squamosal  bone,  and  is  also  termed  the  frontal  arch.  The 
foramen  piercing  the  superior  part  of  this  process  is  the  supra- 
orbital, which  transmits  the  artery,  vein,  and  nerve  of  the  same 
name.  The  thin  plate  which  extends  downwards  and  back- 
wards from  the  external  lateral  border  of  the  bone  is  the  internal 
orbital  i)late  or  jjrocess,  divided  by  a  large  triangular  opening 
closed,  in  the  articulated  state,  by  the  orbital  portion  of 
the  sphenoid;  and  the  small  notch  in  front  of  the  large  one 
forms,  with  the  sphenoid  bone,  the  internal  orbital  foramen. 
The  pit  or  hollow  above  the  larger  notch  lodges  the  lachrymal 
gland  ;  and  the  small  depression  at  the  base  of  the  external  orbital 
process  is  for  the  attachment  of  the  greater  oblique  muscle  of  the ' 
eye.  The  slightly-depressed  part  behind  the  orbital  process  assists 
in  forming  the  temporal  fossa. 

The  internal  surface  is  irregularly  concave,  and  divided  into 
two  unequal  parts  by  a  bony  septum,  the  cranial  plate,  which 
meets  the  cribriform  plate  of  the  ethmoid  bone.  The  posterior 
division  is  smooth,  and  marked  by  ridges,  which  correspond  with 
the  convolutions  of  the  brain,  the  anterior  lobe  of  which  it  covers  ; 
a  furrow  for  the  anterior  meningeal  artery  runs  upwards  from 
the  internal  orbital  foramen,  and  close  to  the  ethmoid  bone. 
The  continuation  of  the  longitudinal  groove  of  the  parietal  bone 


TEMPORAL    BONE.  49 

runs  along  the  median  line  ;  and  near  the  inner  surface  of  the 
orbital  plate  is  a  longitudinal  notch,  the  incisura  sphenoidaliSy 
into  which  the  orbital  portion  of  the  sphenoid  bone  is  received. 
The  anterior  concavities  form  the  frontal  sinus,  which  is  separ- 
ated from  its  fellow  by  a  prominence  termed  the  nasal  spine, 
on  the  posterior  part  of  which  is  a  rounded  surface,  which  joins 
the  crista  galli  process  of  the  ethmoid  bone. 

The  posterior  border  is  divided  into  two  parts,  both  of  which 
are  denticulated,  the  superior  part  articulating  with  the  parietal, 
while  the  inferior  or  descending  part  is  overlapped  by  the 
squamosal  bone.  The  anterior  border  is  pointed  at  the  frontal 
suture,  and  articulates  partly  with  the  nasal  and  partly  with  the 
lachrymal  bone.  The  internal  border  is  straight  and  triangular, 
the  widest  part  being  at  the  septum ;  it  joins  its  fellow.  The 
outer  and  inferior  border  is  very  irregular,  and  articulates  with 
the  sphenoid  and  lachrymal  bones.  The  frontal  bone  articulates 
with  nine  bones  : — its  fellow,  the  parietal,  squamosal,  sphenoid, 
ethmoid,  lachrymal,  nasal,  palatine,  and  superior  maxillary  bones. 

TEMPORAL    BONE. 
"(Fig.  12.  4,  5.) 

Situated  at  the  side  of  the  cranium,  the  temporal  bone  is  divided, 
in  the  horse,  into  two  distinct  pieces,  named  the  squamosal  or 
squamous  temporal  and  the  petrosal  or  petrous  temporal  bones.- 

The  Squamosal  bone  (Fig.  10.  III.)  is  irregularly'  oval, 
flattened,  and  slightly  curved,  with  a  strong  process  arching  out- 
wards and  forTvards.  It  has  an  external  and  an  internal,  or 
cerebral  surface,  and  a  circumferent  border. 

The  external  surface  is  rather  convex,  presenting  numerous 
small  foramina,  which  lead  into  the  parie to-temporal  conduit,  a 
cavity  between  it  and  the  parietal  bone.  Projecting  outwards 
and  forwards  from  its  middle  is  a  long,  arched  f  process,  the 
zygomatic,  which  unites  with  a  similar  process  of  the  malar  bone 
to  form  the  zygomatic  arch,  on  which  the  frontal  arch  abuts 
superiorly.  Posterior  to  this  abutment  is  a  broad  convex  surface, 
which  forms  the  inferior  part  of  the  temporal  fossa  ;  and  pro- 
jecting upwards  from  the  postero-external  part  of  the  fossa  is  the 
sharp  zygomatic  spine.  The  shallow  transverse  concavity  on  the 
inferior  face  of  the  zygomatic  process  is  the  glenoid  cavity,  with 
.which  the  condyle  of  the  lower  jaw  articulates  ;  and  continuous 

£ 


50  OSTEOLOGY. 

with  this  cavity,  anteriorly,  is  an  articular  ridge,  the  condyle, 
which  also  forms  part  of  the  articulation,  and  posteriorly  the 
anterior  mastoid  process,  which  limits  the  motion  of  the  articu- 
lation ;  the  opening  of  the  parieto-temjjoral  conduit  or  canal  is 
at  the  base  of  the  process.  Posteriorly,  the  bone  divides,  the 
inferior  portion  being  beaked,  and  clasping  the  external  auditory 
meatus  of  the  petrosal  bone,  and  the  other  extending  backwards, 
to  articulate  with  the  occipital,  the  occipital  ridge  becoming 
continuous  with  the  prolongation  of  the  zygomatic  spine. 

The  internal  surface  is  divided  into  two  very  unequal  portions 
by  a  deep  channel,  which  forms,  with  the  parietal  and  petrosal 
bones,  the  temporal  or  parieto-temporal  conduit.  The  posterior 
portion  articulates  with  the  petrosal  bone,  while  the  posterior 
half  of  the  anterior  and  larger  portion  is  greatly  roughened  and 
bevelled,  superiorly,  forming  with  the  parietal  bone  the  squamous 
suture  of  the  skull :  such  of  the  remaining  portion  as  forms  part 
of  the  wall  of  the  cranial  cavity  is  marked  similarly  to  the  internal 
surface  of  the  other  cranial  bones ;  the  remainder  articulates 
with  the  ali-sphenoid  bone. 

Thus  the  squamosal  bone  articulates  with  the  petrosal,  parietal, 
occipital,  frontal,  sphenoid,  malar,  superior  and  inferior  maxillary 
bones. 

The  Petrosal  bone  is  the  hardest  bone  in  the  skeleton,  and 
is  interesting,  as  it  contains  the  essential  part  of  the  organ  of 
hearing.  It  is  a  small,  thick  bone,  somewhat  pyramidal  in  shape, 
the  base  being  turned  downwards  and  a  little  backwards,  and  it 
is  placed  at  the  postero-lateral  part  of  the  cranium  between  and 
below  the  occipital,  parietal,  and  squamosal  bones.  It  presents 
four  surfaces,  a  summit,  and  a  base. 

The  anterior  .surface  is  divided  into  two  portions,  the  more 
external  part  being  roughened,  and  articulating  by  harmony  with 
the  parietal  bone,  while  the  inner  and  lesser  portion  is  smooth, 
and  forms  the  posterior  part  of  the  cavity  for  the  greater  lobe  of 
the  cerebrum.  The  posterior  surface  is  triangular  and  rough, 
and  articulates  by  harmony  with  the  occipital  bone.  The  external 
surface,  also  triangular,  is  divided  into  two  parts,  the  inner 
articulating  with  the  squamosal,  the  outer  being  interposed  between 
the  occipital  ridge  and  the  styloid  process  of  the  occipital  bone. 
The  internal  surface,  which  forms  the  lateral  boundary  of  the 
cavity  for  the  cerebellum,  is  slightly  concave,  and  presents  several 
depressions,  and  anteriorly  a  large  orifice  and  conduit,  the  internal 


TEMPORAL    BONE.  51 

<iuditory  meat-tis — a  short  canal  through  which  the  auditory  and 
facial  motor  nerves  pass,  and  which  is  divided  by  a  thin  plate 
into  two  parts,  one  leading  by  small  foramina  to  the  internal  ear, 
the  other  being  the  origin  of  the  aqueduct  of  Fallopius,  which, 
after  taking  a  spiral  course  through  the  bone,  terminates  externally 
by  the  stylo-mastoid  foramen.  A  narrow  slit,  the  aqueduct  of 
the  vestibule;  near  the  meatus,  transmits  a  small  vein  and  artery, 
and  lodges  a  process  of  dura  mater. 

The  four  surfaces  are  separated  by  four  borders  or  angles,  two 
of  which  deserve  notice, — the  first,  separating  the  external  from 
the  posterior  surface,  is  thick  and  rough,  and  forms  the  mastoid 
ridge,  which  is  continuous  with  the  occipital  ridge  above, 
and  has  the  posterior  mastoid  process  in  front;  the  mastoid 
fissure  runs  across  this  angle,  passing  upwards  under  the  squa- 
mosal bone  to  terminate  in  the  parieto-temporal  conduit.  The 
second,  separating  the  anterior  from  th^/  internal  surface,  marks 
the  division  between  the  cavities  of  the  cerebrum  and  cerebellum, 
and  has  a  process  of  dura  matter  attached. 

The  summit  of  the  bone  is  pointed,  and  articulates  with  the 
occipital ;  the  hase  is  very  irregular  in  outline,  and  presents  a 
large  opening,  the  external  auditory  meatus,  which  leads  to 
the  middle  ear,  and  is  surrounded  by  an  oval  rim  of  bone, 
which  is  notched  in  the  middle,  and  gives  attachment  to  the 
cartilages  of  the  ear.  Below  this  opening  is  the  hyoid  process, 
to  which  is  attached  the  comu  of  the  hyoid  bone,  and  between 
which  and  the  mastoid  process  is  the  stylo-mastoid  foramen,  the 
external  opening  of  the  aqueduct  of  Fallopius.  The  rounded 
part  immediately 'below  the  hyoid  process  is  the  mastoid  'pro- 
tuberance or  auditory  bulla,  which  is  little  developed  in  the 
horse,  containing  the  mastoid  cells ;  before,  and  projecting 
forwards,  is  the  long  and  slender  styloid  process,  which  gives 
attachment  to  muscles,  the  Glaserian  fissure  (styloid  foramen) 
for  the  corda  tympani  nerve  being  above  it,  and  the  opening  for 
the  Eustachian  tube  below  and  inside.  More  internally,  a  well- 
marked  ridge  forms  the  external  boundary  of  the  foramen  lacerum 
basis  cranii. 

The  petrosal  bone  articulates  with  the  occipital,  parietal,  and 
squamosal  bones,  and  with  the  hyoidean  cornu. 


52  OSTEOLOGY. 

SPHENOID. 

(Fig.  13.  8.) 

This  is  a  single  bone  situated  in  the  middle  and  anterior  parts  of 
the  base  of  the  cranium,  between  the  occipital  and  ethmoid  bones, 
and  transversely  between  the  two  frontal  and  temporal  bones.  Its 
shape  is  generally  likened  to  that  of  a  bird  in  flight,  with  its  legs 
and  wings  extended,  in  the  young  state  this  bone  separates 
readily  into  two  parts,  an  anterior  and  a  posterior.  Anatomically, 
it  may  be  divided  into  two  centre-pieces,  and  two  pairs  of 
flattened  processes  or  wings.  The  posterior  centre-piece  is  then 
termed  the  basi-sphenoid.  articulating  behind  with  the  basi- 
occipital,  and  before  with  the  other  centre,  the  pre-sphenoid,  the 
two  constituting  the  body  of  the  bone.  The  expanded  parts, 
collectively-  termed  the  wlngSj  are  formed  of  two  plates  from  the 
posterior  centre  called  the  ali-sphenoid,  and  two  considerably 
larger  ones  from  the  anterior  centre,  the  orbito-sphenoid  bones. 
Although  for  descriptive  purposes  it  may  be  sufficient  to  divide 
the  bone  into  a  body  and  two  wings,  still  it  is  well  to  bear  in 
mind  the  above  divisions  and  names. 

The  body  is  semi-cylindroid  in  form,  convex  inferiorly,  where 
it  is  roughened  for  muscular  attachments,  and  on  either  side  is 
the  long  pterygoid  process,  continuous  with  the  posterior  wing. 
On  each  side  of  the  body,  and  winding  round  to  the  anterior  part 
of  the  pterygoid  process,  is  a  small  groove,  the  Vidian  fissure, 
which  the  palatine  bone  converts  anteriorly  into  the  small  Vidian 
canal,  through  which  the  nerve  of  that  name  passes  to  join  the 
spheno-palatine  ganglion.  Above  this  fissure,  and  passing  through 
the  base  of  the  pterygoid  process,  is  the  large  pterygoid  foramen, 
which  bifurcates  anteriorly,  the  larger  and  inferior  branch  giving 
passage  to  the  internal  maxillary,  while  the  smaller,  which  is 
directed  upwards,  lodges  the  anterior  deep  temporal  artery ; 
and  in  front  of  the  process  is  a  large  irregular  opening,  the  orbital 
hiatus,  into  which  various  foramina  open.  Still  more  anteriorly 
is  the  optic  foramen  ;  and  at  the  anterior  border  of  the  body,  a 
notch,  which  with  the  frontal  bone,  forms  the  internal  orbital 
foramen,  giving  passage  t«)  branches  of  the  ophthalmic  artery  and 
nerve. 

The  internal  or  superior  surface  is  smooth,  and  presents, 
in  the  posterior  segment  of  the  body,  a  shallow  fossa,  the  pituitary 


SPHENOID.  53 

fossa  or  sella  turcica,  in  which  the  pituitary  gland  is  lodged  ;  in 
front  of  the  sella  turcica  is  a  slight  elevation  formed  by  the  pre- 
sphenoid,  the  olivary  process,  which  supports  the  commissure  of 
the  optic  nerves.  Immediately  in  front  of  the  olivary  process  is 
the  optic  hiatus,  a  transverse  notch  which  leads  to  the  two  optic 
foramina  for  the  optic  nerves  ;  and  anteriorly  is  a  sharp  central 
process  which  articulates  with  the  crista  galli  process  of  the 
ethmoid  bone.  A  concavity  on  each  side  of  the  anterior  part  of 
the  body  helps  to  form  the  ethmoid  fossa,  which  contains  the 
olfactory  bulb. 

On  each  side  of  the  sella  turcica  are  two  shallow  grooves,  the 
internal  being  the  cavernous  fossa,  which  contains  the  cavernous, 
sinus  of  the  brain,  and  the  ophthalmic,  third,  and  sixth  nerves ; 
the  external,  which  is  the  larger  and  deeper,  is  the  sphenoidal 
fossa,  which  transmits  the  superior  maxillary  division  of  the  fifth 
nerve.  In  front  of  these  lateral  grooves,  and  continuous  with 
them,  two  foramina  open  into  the  orbital  hiatus,  the  inner  and 
uppermost  being  the  foramen  lacerwm  orbitale,  for  the  alveolar 
vein,  and  the  third  and  sixth  nerves  ;  the  inferior  is  the  foramen 
rotnndum  for  the  passage  of  the  superior  maxillary  division  of 
the  fifth  nerve ;  it  is  joined  by  the  pterygoid  foramen.  Above 
these,  and  passing  through  the  base  of  the  pterygoid  process,  the 
foramen  patheticum  gives  passage  to  the  fourth  nerve 

The  wings'  project  outwards  and  upwards;  their  internal  sur- 
faces are  smooth,  and  help  to  form  the  lateral  walls  of  the 
cranium,  the  posterior  part  being  hollowed  for  the  mastoid  lobes 
of  the  cerebrum.  The  external  surface  of  the  wing  is  slightly- 
convex  anteriorly,  where  it  joins  the  frontal  bone  to  form  the 
orbital  fossa,  and  rough  posteriorly,  where  it  articulates  with  the 
squamosal  bone.  The  pterygoid  processes  project  downwards  and 
forwards,  are  broad  and  flat,  and  articulate  with  the  vomer  and 
palatine  bones. 

The  posterior  border  of  the  body  articulates  with  the  basi- 
occipital  bone.  The  portion  of  the  wing  next  to  the  body  bounds 
anteriorly  the  foramen  lacerum  basis  cranii ;  in  this  portion  there 
are  two  notches,  an  internal  one,  the  carotid  notch,  which  gives 
passage  to  the  endocarotid  artery,  and  is  continued  under  the 
body  of  the  bone,  and  an  external,  the  inferior  maxillary  notch, 
which  transmits  the  nerve  of  the  same  name,  a  branch  of  the 
fifth. 

The  anterior  face  of  the  body  of  the  bone  presents  two  deep 


54  OSTEOLOGY. 

cavities  separated  by  a  thin  bony  plate,  sometimes  perforated, 
"which  is  continuous  with  the  perpendicular  plate  of  the  ethmoid 
bone  ;  these  cavities  are  the  sphenoidal  cells,  and  help  to  form 
the  sphenoidal  sinuses.  The  sphenoid  bone  articulates  with 
thirteen  bones — the  occipital,  ethmoid,  and  vomer,  single  bones : 
and  the  superior  maxilla,  frontal,  parietal,  squamosal,  and  ptery- 
goid, pairs. 

ETHMOID. 

(Fig.  13.  7.) 

The  ethmoid,  or  sieve-like  bone,  is  placed  between  the  frontal 
-and  sphenoid  bones ;  it  separates  the  nasal  fossse  from  the 
cranium,  and  consists  of  a  perpendicular  plate  and  two  lateral 
portions. 

The  perpendicular  plate  or  lamella,  continuous  with  the  carti- 
laginous septum  of  the  nose,  is  covered,  excepting  in  the  cranium, 
'with  pituitary  membrane ;  it  divides  the  sphenoidal  sinuses,  is 
-continuous  with  the  septum  dividing  the  frontal  sinuses,  and  it 
joins  the  vomer  below.  Posteriorly,  it  forms  the  crista  galli 
jprocess,  which  projects  upwards  in  front  of  the  cranial  cavity,  is 
narrow  inferiorly,  where  it  joins  the  sphenoid,  and  broad  sup- 
eriorly, where  it  supports  the  frontal  bone. 

The  ethmoid  cells  constitute  the  lateral  parts  of  the  bone. 
These  are  numerous  and  very  fragile  plates  of  bone  rolled  up 
into  conchse  or  volutes,  which  contain  the  ethmoid  sinuses,  and 
-are  attached  to  transverse  plates.  The  cribriform  plates,  which 
are  perforated  for  the  passage  of  the  olfactory  nerves,  separate  the 
cranial  from  the  nasal  cavities.  The  concave  posterior  parts 
ibrm  the  ethmoidal  fossce,  the  most  anterior  recesses  of  the 
cranium,  which  are,  in  the  fresh  state,  occupied  by  the  olfactory 
bulbs.  The  ethmoid  articulates  with  ten  bones — the  sphenoid, 
corner,  two  frontals,  two  palatines,  two  superior  turbinals,  and  two 
superior  maxillaries. 

FACIAL   BONES. 

The  facial  skeleton  consists  of  two  parts,  the  superior  and 
inferior  maxillary,  the  regions  respectively  of  the  upper  and  lower 
jaw,  each  of  which  supports  the  passive  organs  of  mastication, 
the  teeth.  The  upper  portion,  whiclj  is  traversed  by  the  nasal 
-cavities,  is  formed  of  nineteen  distinct  bones,  one  only  of  which. 


NASAL    BONE.  6  5' 

the  vomer,  is  single,  the  remainder — viz.,  the  nasal,  superior 
maxillary,  premaxillary,  malar,  lachrymal,  palatine,  pterygoid, 
and  turbinal  bones  being  pairs.  The  lower  jaw  is  a  single  bone, 
also  called  the  inferior  maxilla  or  mandible,  and  it  include* 
between  its  rami  the  hyoid  bone  and  its  appendices. 


NASAL   BONE. 
(Fig.  10.  v.;   12.  9,  11.) 

The  nasal  bones  are  situated  at  the  autero-superior  part  of  the 
face,  immediately  before  the  frontal  bones,  and  between  tbem 
and  the  lachrymals  and  superior  maxilla.  They  are  long  slender 
bones,  flattened  from  above  downwards,  somewhat  triangular  irt 
form,  and  heart-shaped  when  together.  A  nasal  bone  presents; 
two  surfaces,  two  borders,  a  base,  and  an  apex. 

The  superior  or  external  surface  is  smooth,  convex  from  one 
side  to  the  other,  and  becomes  gradually  larger  posteriorly.  The 
internal  surface  is  concave,  and  forms  the  roof  of  the  nasal  fossa;. 
a  vertical  ridge,  to  which  the  superior  turbinal  bone  is  attached,, 
runs  along  its  external  border;  posteriorly,  this  ridge  bifurcates., 
and  behind  and  within  the  bifurcation  is  a  concave  surface-^ 
which  forms  the  nasal  or  anterior  portion  of  the  frontal  sinus. 
Above  this  ridge  the  surface  is  smooth,  and  forms  a  gutter,  the 
superior  nasal  meatus,  and  along  the  inner  border  is  a  slight 
ridge,  which  combines  with  that  of  the  opposite  bone  to  form  a. 
groove  for  the  cartilaginous  septum  nasi. 

The  internal  border  is  straight  and  dentated,  and  articulates-, 
with  its  fellow.  The  external  border  is  very  thin  and  waved,, 
dentated  in  its  upper  two-thirds  to  articulate  with  the  lachrymal 
bone,  the  superior  maxilla,  and  the  posterior  part  of  the  pre- 
maxilla,  the  remaining  part  being  free,  so  as  to  leave  an  angular- 
opening,  the  naris,  between  it  and  the  premaxilla.  The  base 
or  superior  border  is  rounded,  serrated,  and  unites  with  the 
frontal  ;  the  apex  is  sharp  and  pointed,  forming  vdth  its  fellow 
the  nasal  peak. 

The  nasal  bone  articulates  with  the  frontal,  lachrymal,  superior 
Taaxillary,  premaxillary,  and  opposing  nasal  bones,  and  has  the. 
superior  turbinal  bone  attached  to  its  inner  surface. 


56  OSTEOLOGY. 

SUPERIOR    MAXILLA. 

(Fig.  12.  8;  Fig.  13.  14.) 

This  is  situated  at  the  side  of  the  face,  and  is  the  largest  bone 
of  the  upper  jaw,  very  irregular  in  form,  and  elongated  from 
before  backwards.  It  presents  three  surfaces,  three  borders,  and 
two  extremities. 

The  external  or  facial  surface,  concavo-convex  in  the  adult,  and 

somewhat  convex  in  the  young  animal,  is  almost  smooth,  having 

an  elongated   horizontal  ridge,  the  maxillary  spine,  continuous 

with  the  zygomatic  spine  of  the  malar  bone,  commencing  opposite 

the  third  molar  tooth,  and  running  along  the  middle  line  of  the 

posterior  part  of  the  surface.      Near  the  middle  of  the  upper  surface 

is  the  large  infra- orbital  foramen,  through  which  the  facial  division 

■of  the  fifth  nerve  and  a  branch  from  the  superior  dental  artery 

pass.     The  inferior  or  palatine  surface,  slightly  hollowed  from 

side  to  side,  consists  of  a  bony  plate,  the  palatine  process,  which 

forms  the  greater  part  of  the  bony  palate,  orpartition  between 

the  nasal  fossae  and  the  mouth ;   it  contains  numerous  small 

grooves  and  foramina,  and  one  deep  groove  near  its  outer  edge, 

the  palatine,  which  is  bounded  by  the  alveolar  processes  of  the 

molar  teeth,  and  runs  the   whole   length  of   the  bone,  giving 

passage  to  the  palatine  artery.      The  internal  or  nasal  surface 

forms  the  sides  and  most  of  the  floor  of  the  nasal  cavity  ;  it  is 

irregularly  concave,  smooth,  and  divided  into  two  concavities  by 

.a  longitudinal  ridge,  the  internal  maxillary  spine,  to  which  the 

inferior  turbinal  bone  is  attached.   At  the  posterior  part  of  this 

:surface  is  a  large,  deep  excavation,  the  maxillary  sinus,  below 

which  is  a  serrated  surface,  articulatingwith  the  palatine  bone, 

and  cantaining  a  fissure,  which,  with  a  corresponding  fissure  in 

the  palatine  bone,  forms  the  palatine  foramen.   A  little  anterior 

to  the  sinus  is  the  opening  of  the  lachrymal  conduit,  which  is 

continued  by  a  shallow  fissure  to  the  anterior  extremity  of  the 

bone  ;  along  this  conduit  and  fissure  passes  the  lachrymal  duct, 

which  conveys  the  tears  from  the  eye  to  the  nasal  chamber. 

The  superior  border  is  thin,  convex,  and  divided  into  two 
parts — an  anterior,  grooved  and  serrated  for  the  attachment  of 
the  external  border  of  the  nasal  bone,  and  the  inferior  part  of 
the  premaxilla,  and  a  posterior,  which  is  bevelled  to  articulate 
-with  the  lachrymal  and   malar  bones.     The  infemor  border  is 


PREMAXILLA.  57 

'\ery  thick,  and  contains  six  quadrilateral  cavities,  termed  alveoli, 
in  which  the  upper  molar  teeth  are  lodged.  At  the  back  of  thq 
last  alveolus  is  a  large  rounded  eminence,  the  alveolar  tuberosity;, 
and  in  front  of  the  first  the  border  becomes  thin  and  sharp,  and 
forms  a  portion  of  the  diastema  or  interdental  space,  which 
separates,  the  molar  from  the  incisor  and  canine  teeth.  The 
internal  border  is  serrated  to  articulate  with  its  fellow  of  the 
opposite  side,  notched  anteriorly  to  form  the  incisive  opening, 
and  it  articulates  posteriorly  with  the  palatine  bone. 

The  posterior  extremity  is  rounded  and  prominent,  forming 
the  alveolar  tuberosity,  in  the  interior  of  which  the  maxillary 
sinus  is  prolonged.  At  the  inner  side  of  this  eminence  is  a  large 
deep  excavation,  which  the  palatine  bone  assists  to  form  into  the 
maxillary  hiatus.  This  hiatus  is  situated  directly  opposite  to 
the  orbital  hiatus,  the  spheno-maxillary  fissure  being  the  space 
between  them;  the  hiatus  contains  three  foramina — 1st,  the 
palatine  or  palato-maxillary,  which  leads  to  the  palatine  groove, 
for  the  passage  of  the  palatine  artery  ;  2nd,  the  dental,  which 
enters  the  maxillary  sinus,  is  continued  along  the  roots  of  the 
molar  teeth,  and  divides  into  two  branches — a  large  short  one, 
which  opens  at  the  infra-orbital  foramen,  and  another  continued 
to  the  roots  of  the  incisor  teeth  ;  the  3rd  is  the  spheno-palatine, 
which  enters  the  nasal  chamber,  and  gives  passage  to  the  spheno^ 
palatine  artery,  vein,  and  nerve.  The  anterior  extremity  pre- 
sents in  the  male  a  cavity  which,  with  a  similar  cavity  in  the 
premaxilla  with  which  it  articulates,  forms  the  alveolus  of  the 
canine  tooth. 

The  superior  maxilla  articulates  with  its  fellow,  and  with  the 
premaxilla,  ethmoid,  squamosal,  nasal,  palatine,  malar,  lachrymal, 
and  inferior  turbinal  bones. 

PREMAXILLA. 

(Fig.  12.  10.) 

This  bone,  called  also  the  Inter  or  Anterior  maxillary  bone, 
is  situated  at  the  anterior  extremity  of  the  face,  and  consists  of 
a  broad  thick  part  and  two  processes  which  spring  from  it. 
The  thick  part  or  base  presents  three  surfaces — an  external 
or  labial,  which  is  smooth  and  convex  ;  an  internal,  which  is 
roughened  to  articulate  with  its  fellow,  and  has  a  groove  running 
down    it,    which,   with   that   of   the    opposing    bone,   forms  the 


58  OSTEOLOGY. 

foramen  incisivum  for  the  passage  of  the  palato-labial  artery  j 
and  an  inferior,  which  is  smooth^  slightly  concave,  and  marked 
by  a  continuation  of  the  palatine  groove,  which  terminates  in  the 
foramen  incisivum.  Between  the  external  and  inferior  surfaces 
is  a  very  thick  curved  border,  containing  anteriorly  three  alveoli 
for  the  incisor  teeth,  behind  which  is  a  sharp  portion,  which  helps 
to  form  the  interdental  space.  At  the  posterior  part  of  the 
border,  in  the  male  animal,  there  is  a  cavity  which,  with  that  on 
the  anterior  extremity  of  the  superior  maxilla,  forms  the  alveolus 
for  the  canine  tooth. 

The  processes  are  external  and  internal.  The  external,  the 
largest  and  longest,  is  continuous  with  the  base,  and  flattened 
from  side  to  side.  Its  outer  surface  is  convex  and  smooth,  its 
inner  rounded  above,  and  covered  by  the  mucous  membrane  of 
the  nasal  chamber  ;  inferiorly,  it  is  roughened  to  articulate  with 
the  superior  maxilla  ;  its  posterior  extremity  is  thin,  and  attached 
between  the  superior  maxilla  and  the  nasal  bone.  The  internal 
or  palatine  process  is  a  thin  flexible  plate,  which  joins  its  fellow 
internally  by  a  dentated  suture  ;  their  superior  surface  forms  part 
of  the  floor  of  the  nasal  fossae,  and  their  inferior  part,  which  is 
smooth,  forms  part  of  the  hard  palate. 

The  premaxillae  are  joined  by  fibro-cartilage  in  the  young 
animal  and  by  ossification  in  the  old,  the  junction  forming  the 
symphysis  ;  they  articulate  with  each  other  and  with  the  superior 
maxilla,  nasal  bone,  and  vomer. 

MALAR   BONE. 
(Fig.  12.  7.) 

The  Malar,  Zygomatic,  or  Jugal  bone,  situated  at  the  antero- 
inferior part  of  the  orbital  fossa,  is  irregularly  triangular  in  shape, 
with  a  broad  anterior  part,  ending  in  a  sharpened  posterior  point. 
It  presents  for  consideration  three  surfaces,  a  base,  and  the 
zygomatic  process. 

The  external  or  facial  surface  is  smooth,  somewhat  convex, 
and  has,  inferiorly,  a  sharp  ridge,  the  zygomatic  ridge,  continued 
posteriorly  by  the  zygom.atic  process,  which  meets  the  process  of 
the  same  name  of  the  squamosal  bone,  the  two  forming  the 
zygomatic  arch.  The  internal  or  maxillary  surface  is  irregularly 
concave,  the  posterior  part  helping  to  enclose  the  maxillary  sinus. 
The  superior  or  orbital  surface  is  concave,  and  forms  the  antero- 


PALATINE    BONE. 


69 


inferior  part  of  the  orbital  fossa,  the  border  which  separates  it 
from  the  external  surface  being  part  of  the  orbital  ridge.  The 
base  is  thin,  and  articulates  with  the  superior  maxilla,  and  above 
the  base  is  a  serrated  border  which  articulates  with  the  lachrymal 
bone. 

The  malar  articulates  with  the  superior  maxilla,  the  lachrymal, 
and  squamosal  bones. 

LACHETMAL    BONE. 
(Fig.  12.  6.^ 

This  is  situated  at  the  supero-auterior  part  of  the  orbital  fossa ; 
it  is  an  irregular  bone,  very  tbin  and  very  light,  and  presents 
three  surfaces  and  a  circumference. 

The  external  or  facial  surface  is  triangular,  slightly  convex, 
and  bounded,  posteriorly,  by  the  orbital  ridge,  in  the  middle  of 
which  is  an  eminence,  the  Idchrymal  tubercle,  to  which  the 
orbicularis  palpebrarum  muscle  is  attached.  The  posterior  or 
orbital  surface,  also  triangular,  is  concave  and  smooth;  it  presents 
near  its  centre  a  funnel-shaped  cavity,  the  lachrymal  fossa,  \i\i\c\\ 
leads  to  the  lachrymal  canal,  and  gives  lodgment  to  the  lachrymal 
sac.  The  lesser  oblique  muscle  of  the  eye  is  attached  in  a  slight 
depression  at  the  inner  side  of  this  cavity.  The  internal  surface 
IS  divided  by  the  prominent  wall  of  the  lachiymal  canal  into  two 
concavities,  and  forms  part  of  the  roof  of  the  maxillary  sinus. 
The  circumference  is  very  rough,  and  denticulated  for  articulat- 
ing with  the  frontal,!  nasal,  superior  maxillary,  and  malar  bones. 

PALATINE    BONE. 
(Fig.  13.  11.) 

This  bone  is  situated  at  the  posterior  part  of  the  palatine  plate 
of  the  superior  maxilla,  and  forms,  with  its  fellow,  the  anterior 
and  external  boundaries  of  the  posterior  nares.  It  is  a  long 
narrow  bone,  flattened  from  side  to  side,  and  curved  inwards 
anteriorly,  to  meet  the  opposite  palate  bone,  where  it  becomes 
flattened  horizontally.  It  presents  four  surfaces  and  two  extre- 
mities. 

The  external  or  orh'tal  surface  is  smooth  posteriorly,  where  it 
forms  part  of  the  orbital  fossa,  and  aids  in  the  formation  of  the 
maxilliary  hiatus,  and  denticulated  anteriorly,  where  it  articulates 
with   the    superior    maxilla.        Infero-posteriorly    it    presents    a 


60  OSTEOLOGY. 

shallow  groove,  running  obliquely  downwards  and  forwards,  and 
terminating  in  the  palatine  surface ;  bounded  externally  by  th« 
alveolar  tuberosity  of  the  superior  maxilla,  it  forms  the  staphy 
line  groove  for  the  passage  of  the  staphyline  artery  and  nerve, 
and  the  palatine  vein.  In  the  centre,  also  running  obliquely 
downwards  and  forwards,  is  a  deep  groove,  which,  with  a  similar 
groove  in  the  superior  maxilla,  forms  the  palatine  foramen.  The 
spheno-palatine  foramen  is. in  its  superior  middle.  The  inferior 
or  palatine  surface  is  smooth,  very  narrow,  and  concave,  and  forms 
half  of  the  palatine  arch.  The  internal  or  nasal  surface  is  smooth 
and  concave,  the  anterior  portion  being  narrow,  and  bent  inwards 
to  meet  its  fellow  ;  the  posterior  part  being  broad,  and  presenting 
a  roughened  line,  which  runs  obliquely  from  above  downwards 
for  the  attachment  of  the  pterygoid  bone.  The  superior  or 
sphenoidal  surface  is  deeply  excavated,  assisting  in  the  forma- 
tion of  the  sphenoidal  sinus.  The  sharp  ridge  between  this  and 
the  nasal  surface  is  the  palatine  crest,  on  which  the  vomer  rests. 

The  anterior  extremity  is  flat,  and  curved  inwards  to  meet  the 
opposing  palatine  bone  and  palatine  process  of  the  superior  maxilla. 
The  posterior  extremity  is  very  thin  and  sharp,  and  presents  exter- 
naUy  a  depression,  in  which  the  pterygoid  process  of  the  sphenoid 
bone  articulates.  The  space  between  the  palatine  bones  is  termed 
the  posterior  nares,  the  borders  of  the  opening  or  palatine  arch 
giving  attachment  to  the  velum  pendulum  palati. 

The  palatine  articulates  with  its  fellow,  and  with  the  superior 
maxilla,  the  vomer,  pterygoid,  sphenoid,  ethmoid,  frontal,  and 
inferior  turbinal  bones. 


PTERYGOID    BONE. 

This  is  a  very  small  elongated  bone,  flattened  from  side  to  side 
and  slightly  twisted,  situated  on  the  inner  side  of  the  pterygoid 
process  of  the  sphenoid  and  posterior  part  of  the  nasal  surface  of 
the  palatine  bone,  and  below  the  posterior  part  of  the  vomer.  It 
presents  two  surfaces  and  two  extremities. 

The  external  surface  articulates  with  the  palatine  and  pterygoid 
process  of  the  sphenoid  bone ;  the  internal  surface  is  smooth  and 
covered  by  the  pharyngeal  mucous  membrane ;  the  posteri.or  ex- 
tremity is  very  slender,  and  assists  in  forming  the  Vidian  conduit ; 
the  anterior  extremity  possesses  a  blunt  process,  the  sumonit 
which    is   free,    directed    downwards,    and    has   a    groove    at    its 


TURBINATED    BONES.  61 

■extremity  forming  a  pulley,  round  which  the  tendon  of  the  tensor 
palati  muscle  plays. 

VOMER. 

This,  the  only  single  bone  in  the  superior  facial  region,  is  a 
long  bone  constructed  of  two  thin  plates,  with  a  deep  groove 
between,  and  extends  along  the  middle  line  of  the  floor  of  the 
nasal  chambers  from  the  sphenoid  to  the  premaxilla.  It  presents 
two  surfaces,  two  borders,  and  two  extremities. 

The  two  lateral  surfaces,  narrow  anteriorly  and  wider  poste< 
riorly,  are  smooth,  and,  in  the  fresh  state,  covered  by  mucous 
membrane.  The  superior  border  is  deeply  grooved  for  the 
reception  of  the  cartilaginous  septum  of  the  nose  ;  the  inferior 
border  is  sharp  and  smooth  in  its  posterior  half,  where  it  forma 
the  division  between  the  posterior  nares ;  the  remaining  portion 
is  broad,  flat,  and  slightly  dentated  to  articulate  with  the  maxih 
lary  bones.  The  posterior  extremity  is  broad  from  side  to  side, 
convex  below,  and  concave  above,  where  it  opens  out  into  a 
crescentic  border  which  embraces  the  sphenoid,  and  forms  an 
irregular  hiatus  between  the  two  bones  for  the  passage  of  the 
nerves  and  blood-vessels  which  supply  the  septum.  The  ante- 
rior extremity  is  flat,  and  rests  on  the  palatine  process  of  th* 
premaxilla. 

The  vomer  articulates  with  the  sphenoid,  ethmoid,  palatine, 
pterygoid,  superior  maxillary,  and  premaxillary  bones. 


TURBINATED    BONES. 
(Fig.  13.  6,  12.) 

These,  also  called  the  turbinals,  four  in  number,  one  superior 
and  one  inferior  on  each  side,  are  found  in  the  nasal  chambers, 
and  are  irregular  bony  columns,  larger  posteriorly  than  anteriorly, 
flattened  from  side  to  side,  and  hollowed  within,  dividing  the 
nasal  passages  into  superior,  middle,  and  inferior  meati. 

The  superior  or  ethmoidal  turbinal  is  attached  to  the  ridge 
on  the  nasal  bone  and  to  the  ethmoid,  and  the  inferior  or 
maxillary  turbinal  to  the  ridge  on  the  superior  maxilla.  They 
are  formed  of  very  delicate  and  reticulated  rolls  or  convolutions 
of  bone  void  of  periosteum.  The  superior  is  uhe  larger  of  the 
two,  and  extends  from  the  ethmoid  to  near  the  external  opening  of 


62  OSTEOLOGY. 

the  nose  ;  a  transverse  plate  divides  it  into  two  portions,  of  whicb 
the  posterior  is  continuous  with  the  frontal  sinus,  and  the  anterior 
with  the  nose;  the  convolutions  of  this  bone  are  from  below 
upwards.  The  inferior  bone  is  convoluted  from  above  down- 
wards, and  its  anterior  is  continuous  with  the  maxillary  sinus. 

The  use  of  the  turbinals  is  to  augment  the  surface  of  the  nasal 
chambers  over  which  the  olfactory  nerves  are  distributed,  while, 
by  their  lightness,  they  do  not  add  materially  to  the  weight. 
The  superior  meatus  of  the  nasal  fossa  is  between  the  upper  bone 
and  the  roof  of  the  fossa  ;  the  middle  meatus  is  between  the  two 
bones,  and  the  inferior  meatus  between  the  lower  bone  and  the 
floor. 

INFERIOR    MAXILLA. 

(Fig.  14.) 

This,  the  Mandible,  or  lower  jaw,  is  a  large,  irregular,  somewhat 
V-shaped  bone,   situated  below  the  upper  jaw,  and  articulating. 


Fig.  14. 
Inferior  maxilla  of  Horse— antero-lateral  view,  a,  Body  ; 
b  b',  Rami;  c.  Neck  ;  d,  Mental  Foramen  :  c,  fJucclaator,  and 
«',  Masseter  surface  ;  //',  Inner  Surface  of  Ramus  ;  g,  Molar 
alveoli  ;  /,  Anterior  border  ;  g",  Bar,  bounding  diastema ; 
h  h'  h".  Posterior  border.  The  angle  lies  between  h'  and  h" ; 
i  i,  Condyles  ;  fc  fc,  Coronoid  processes  :  I,  Maxillary  space  ;  m. 
Inferior  dental  foramen  ;  n,  Sigmoid  notch. 

by  means  of  a  true  joint,  with  the  glenoid  cavities  of  the  squamosal 
bone.  It  consists  of  two  symmetrical  branches  flattened  laterally, 
and  deeper  posteriorly  than  anteriorly,  the  posterior  portions 
being  curved  upwards,  and  the  anterior  extremities  united,  thus, 
leaving  a  triangular  space  (the  maxillary)  between.  These 
branches,  united  in  the  adult,  are  separate  in  the  foetus,  and 


INFERIOR   MAXILLA.  63 

■each  presents  for  consideration  two  surfaces,  two  borders,  and 
two  extremities. 

The  external  surface  is  smooth  and  rounded  anteriorly,  growing 
gradually  deeper  as  it  proceeds  backwards  ;  the  posterior  part  or 
curved  portion  is  roughened  and  excavated  for  the  attachment  of 
the  masseter  muscle.  The  internal  surface  is  roughened  and 
hollowed  posteriorly,  for  the  attachment  of  the  pterygoid  muscles, 
and  it  presents  a  large  foramen,  the  inferior  maxillary  or  dental, 
leading  to  the  dental  canal,  which  passes  through  the  bone  below 
the  roots  of  the  molar  teeth.  The  anterior  part  of  this  surface  is 
smooth  and  flat,  and  has  a  groove  for  the  attachment  of  the 
buccal  membrane ;  below  the  groove,  some  of  the  muscles  of  the 
tongue  are  attached. 

The  superior  border  is  straight  anteriorly,  and  concave 
posteriorly  ;  the  first  part  contains  six  alveoli  for  the  lower  molars, 
and  the  second,  which  terminates  in  the  coronoid  process  is  thin, 
and  roughened  for  muscular  attachment.  The  inferior  border 
is  also  divided  into  two  portions,  a  straight  and  a  convex  one, 
separated  by  a  prominent  roughened  part  termed  the  angle  of 
the  jaw.  The  anterior  portion  is  rounded  in  the  young  animal, 
but  grows  gradually  thinner  with  age  owing  to  the  outward 
growth  of  the  teeth ;  the  posterior  border  above  the  angle  becomes 
thinner,  and  terminates  in  the  condyle. 

The  posterior  extremity  presents  two  eminences,  a  flat,  thin, 
pointed  one,  the  coronoid  process,  anteriorly  and  a  transverse 
doubly  convex  one,  the  condyle,  posteriorly,  the  two  being  separated 
by  a  deep  notch^  the  sigmoid  or  corono-condyloid.  The  anterior 
extremities,  joined  by  the  maxillary  symphysis,  form  the  body  of 
the  bone.  The  external  or  labial  surface  of  the  body  is  convex, 
and  gives  attachment  to  the  gums  and  labial  muscles,  and  has  a 
line  down  its  middle,  which  marks  the  division  of  the  foetal  bone. 
The  internal  or  buccal  surface,  less  than  the  external,  is  smooth 
and  concave  ;  the  frsenum  of  the  tongue  is  attached  to  its  poste- 
rior part.  The  anterior  border  is  excavated  into  six  alveolar 
cavities  for  the  incisor  teeth ;  and  on  each  side,  farther  back,  it 
presents,  in  the  male  animal,  a  cavity  for  the  canine  tooth, 
small  or  absent  in  the  female.  The  neck  is  the  constricted 
portion  which  joins  the  body  to  the  ramus,  and  it  has  a  more 
or  less  sharp  ridge,  superiorly ;  these  ridges,  or  bars,  occupy 
the  inferior  diastema  or  interdental  space.  On  the  outer  side 
of  the  neck  is  the  anterior  maxillary,  mental,  or  labial  foramen^ 


64  OSTEOLOGY. 

tlie  termination  of  one  part  of  the  dental  canal  which  transmits 
the  inferior  dental  artery  and  inferior  dental  division  of  the 
fifth  pair  of  nerves. 

OS   HYOIDES. 
(Fig.  15.) 

This  is  a  bone  which  supports  the  tongue,  the  pharynx,  and 
the  larynx,  and  is  suspended  downwards  and  foiAvards  between 
the  rami  of  the  lower  jaw ;  it  has  a  fibro-cartilaginous  attach- 
ment to  the  hyoid  process  of  the  temporal  bone.  The  hyoid 
series  is  composed  of  five  distinct  pieces — a  body,  or  hyoid-bona 
proper,  two  cornua  or  horns,  and  two  cornicula  or  lesser  horns. 
The  body  bears  a  striking  resemblance  to  a  spur  or  two-pronged 


Fig.  15. 

Left'aspect  of  the  hyoid  series  of  bones,  a.  Proximal 
end  of  left  cornu  :  6,  Distal  end  of  right  cornu  ;  c,  Proxi- 
mal end  of  comiculum  ;  d,  Hyoid  bone.  The  left  heel- 
process  points  downwards  and  backwards,  the  spur  process 
in  the  opposite  direction. 

fork,  presenting  two  lateral  or  heel  processes,  the  thyro-hyals^ 
directed  backwards  and  downwards,  their  free  extremities  articu- 
lating with  tbe  thyroid  cartilage  of  the  larynx.  The  two  convex 
articular  facets,  where  these  processes  join  the  body,  are  for  the 
cornicula.  Springing  from  the  middle  portion,  anteriorly,  is  a 
long,  sharpened  process,  the  glossohyal  or  spur  process,  which  is 
buried  in  the  substance  of  the  tongue. 

The  cornicula,  or  cerato-hyals,  are  two  short  cylindrical  pieces, 
articulating  at  the  inferior  extremity  with  the  body,  and  at  the 
superior  with  the  cornua. 

The  cornua,  or  stylo-hyals,  are  long,  thin,  flattened  bones,  which 
extend  obliquely  backwards  and  upwards.  The  anterior  extremity 
of  each  cornu  presents  an  articulation  for  the  corresponding  corni- 


APPENDICULAR   SKELETON.  65 

culum,  while  tlie  posterior  extremity  presents  a  kind  of  thick- 
ened elbow  or  curve  inferiorly,  and  terminates  superiorly  in  a 
rounded  extremity,  wliich  is  united  to  the  temporal  bone  by  a 
piece  of  fibro-cartilage.  Among  mammals  the  hyoid  cornua 
attain  perhaps  in  the  horse  the  maximum  of  relative  size. 
Occasionally  a  rudimentary  additional  ossicle  is  found  in  the 
cartilage  between  the  cornu  and  corniculum. 

Various  muscles  connect  the  hyoid  bones  with  the  tongue, 
larynx,  and  pharynx.  It  may  be  noted  here  that  both  the  ali- 
mentary and  respiratory  canals  pass  between  the  hyoid  cornua. 

APPENDICULAR  SKELETON. 

This  division  of  the  skeleton  includes  the  bones  which  belong 
to  the  limbs  or  extremities,  and  those  which  help  to  join  the 
latter  to  the  trunk,  when  such  bony  union  exists.  The  horse, 
like  the  majority  of  mammals,  has  two  pairs  of  limbs — an 
anterior,  fore,  thoracic,  or  pectoral,  and  a  posterior,  hind,  or 
pelvic  pair,  which  have  bones  of  connection,  called  respectively 
the  pectoral  and  pelvic  arches.  In  the  horse,  as  in  many  other 
animals,  there  is  no  articular  connection  between  the  anterior 
limb  and  the  trunk,  hence  tlie  2^edoral  arch  is  incomplete.  The 
actual  attachment  of  this  limb  is  entirely  muscular,  the  body 
being  suspended,  as  it  were,  in  a  muscular  swing  between  the 
anterior  limbs. 

There  is  a  certain  correspondence  between  the  bones  of  the 
front  and  those  of  the  hinder  limb,  as  reference  to  the  skeleton, 
and  the  following  Table  will  show  : — 

Pectoral  Limb.  Pelvic  Llmb. 


Humerus.  . 
(Olecranon). 
Radius  and  Ulna. 
Carpus  (8  bones). 
Metacarpus  (3  bones) 
Phalanges,  3. 
Sesamoids,  3. 


Femur. 

Patella. 

Tibia  and  Fibula. 
Tarsus  (6  bones). 
Metatarsus  (3  bones). 
Phalanges,  3. 
Sesamoids,  3. 


The  humerus  and  femur,  when  the  animal  is  stationary,  slope 
in  opposite  directions,  and  the  two  pairs  of  bones  beneath  them 
appear  to  do  the  same  ;  it  is  probable,  however,  that  the  axis  of 
the  radius  itself  is  as  nearly  perpendicular  as  possible. 


66  OSTEOLOGY. 

The  carpus  and  tarsus  bend  or  flex  in  opposite  directions,  but 
below  these  joints  the  skeleton  of  the  fore  limb  differs  in  no  very 
material  point  from  that  of  the  hinder  one. 

PECTORAL   ARCH. 

The  'pectoral  arch  or  shoulder-girdle  consists,  in  the  horse,  of 
a  bone  called  the  scapula,  on  which  we  find  a  prominent  object, 
the  coracoid  apophysis.  This  process  being  developed  from  a 
distinct  ossific  centre,  is  considered  the  homologue  of  the  coracoid 
bone,  a  bone  which  is  greatly  developed  in  some  animals, 
articulating,  in  some  cases,  with  the  sternum  below.  Another 
bone  that  very  frequently  assists  in  the  formation  of  the  arch,  the 
clavicle  or  collar  bone,  is  altogether  absent  in  the  horse,  as  in  the 
rest  of  the  Ungulata.  On  the  other  hand,  the  pelvic  or  hinder 
limb  is  firmly  attached  to  the  sacrum  by  means  of  the  pelvic 
arch,  which  is  complete. 

PECTORAL    OR   FORE    LIMB. 

Regarding  the  anterior  extremity  as  consisting  of  the  limb 
and  its  incomplete  arch,  the  bones  we  have  to  describe  are 
the  scapula,  humerus,  radius,  and  ulna  ;  the  carpus,  consisting 
of  eight  bones — viz.,  the  cuneiform,  lunar,  scaphoid,  and  trapezium 
in  the  upper  row,  and  the  unciform,  magnum,  trapezoid,  and 
pisiform  in  the  lower  row  ;  three  metacarpal  bones,  two  of  which 
are  imperfect ;  three  sesamoid  bones,  one  pair  and  a  single  one, 
the  latter  called  also  the  navicular  bone  :  and  finally,  three 
phalanges  or  finger  bones,  called  respectively  the  os  sufiraginis, 
OS  coronae.  and  os  pedis. 

SCAPULA. 

(PL.  L  J.) 

The  scapula  is  a  flat  bone  situated  on  the  antero-Iateral 
surface  of  the  thorax,  with  its  long  axis  sloping  downwards  and 
forwards  ;  it  is  triangTilar  in  shape,  the  base  being  turned  up- 
wards. In  the  horse  this  bone  is  strong  but  comparatively  small ; 
it  is  broad  and  thin  superiorly,  becoming  both  narrower  and 
thicker  inferiorly ;  its  position,  or  rather  slope,  is  a  point  of 
importance  in  the  conformation  of  the  animal,  and  varies  to  some 


SCAPULA.  67 

extent,  hut  its  inferior  angle  is  situated  about  the  level  of  the 
first  rib,  the  posterior  angle  being  usually  at  or  near  the  level  of 
the  sixth  or  seventh.  It  ofifers  for  consideration  two  surfaces, 
three  borders,  and  three  angles. 

The  external  surface  or  dorsum  of  the  scapula  is  divided  into 
two  unequal  parts  by  a  crest  running  nearly  the  whole  length 
of  the  bone,  termed  the  spine,  which  at  its  broadest  part  has  a 
roughened  tubercle  to  which  the  trapezius  muscle  is  attached; 
the  clavicle,  in  animals  which  possess  one,  is  attached  to  the 
inferior  extremity  of  the  spine.  The  hollow  part  in  front  of  the 
spine,  the  antea  spinatas  fossa,  receives  the  antea  spinatus 
muscle,  and  the  postea  spinatus  fossa,  the  larger  of  the  two,  is 
occupied  by  the  postea  spinatus  muscle ;  the  nutrient  foramen  is 
in  this  fossa. 

The  internal  or  venter  surface  is  smooth,  though  uneven ;  its 
fossa,  the  fussa  subscapularis,  lodges  the  subscapularis  muscle,  and 
the  rough  triangular  spaces  at  the  upper  angles  give  attachment 
to  the  serratus  magnus  and  rhomboidei  muscles. 

The  superior  border  is  nearly  straight,  roughened,  and  has  the 
broad  cartilage  of  prolongation  fixed  to  it.  The  anterior  border 
is  superiorly  convex  and  sharp,  and  inferiorly  concave  and 
blunted,  and  it  terminates  in  a  large,  rough,  hemispherical,  and 
internally  a  somewhat  bent  process,  the  coracoid  apophysis,  to 
which  the  coraco-humeralis  and  coraco-radialis.  muscles  are 
attached.  This  process  is  formed  from  a  separate  point  of 
ossification.  The  2^osterior  border  is  blunt  and  rough,  and 
affords  attachment  to  several  muscles. 

The  anterior  or  cervical  angle  is  thin,  while  the  posterior  or 
dorsal  angle  is  thick  and  tuberous.  The  inferior  or  humeral 
angle  is  expanded,  and  separated  from  the  rest  of  the  bone  by  a 
constriction  or  neck;  this  extremity  is  the  strongest  part  of  the 
bone,  and  contains  a  shallow,  oval,  articular  depression,  the  glenoid 
cavity,  articulating  with  the  humerus,  and  surmounted  by  a  rim 
of  bone  to  which  the  capsular  ligament  is  attached;  at  its  inner 
■side  there  is  a  notch  for  the  passage  of  blood-vessels. 


68  -  OSTEOLOGY. 

HUMERUS. 
(PL.  I.  K.) 

The  humerus  is  a  long  bone  extending  from  the  scapula  to  th& 
radius,  in  an  oblique  direction,  downwards  and  backv^ards.  Like 
all  long  bones  it  possesses  a  shaft  and  two  extremities. 

The  shaft  or  body  is  characterised  in  most  animals  by  a 
more  or  less  twisted  appearance,  most  apparent  externally  and 
anteriorly.  We  will  describe  it  as  presenting  four  surfaces.  The 
anterior  surface,  somewhat  triangular  in  shape,  with  the  apex 
below,  is  roughened  between  its  middle  and  inferior  third,  for 
the  insertion  of  the  coraco-humeralis  muscle.  The  posterity)^ 
surface,  round  and  smooth,  and  not  clearly  divided  from  the 
internal  and  external  surfaces,  terminates  inferiorly  in  two 
prominent  ridges,  the  epitrochlea  and  epicondyle.  The  external 
surface  contains  the  musculo-spiral  groove,  which  winds  obliquely 
downwards  and  forwards  through  the  entire  length  of  the  shaft. 
This  groove,  which  is  occupied  by  the  humeralis  obliquus 
muscle  gives  the  twisted  appearance  to  the  bone ;  it  is 
separated  from  the  anterior  surface  by  the  deltoid  ridge,  which 
extends  from  the  outer  part  of  the  proximal  end  of  the  shaft 
to  the  coronoid  fossa,  a  depression  in  its  antero-distal  end.  A 
roughened  prominence,  the  external  tuberosity,  on  the  upper 
third  of  this  ridge,  bends  backwards  over  the  spiral  groove,  and 
gives  attachment  to  the  teres  extemus  muscle.  The  internal 
surface  has  no  distinct  separation  from  the  anterior  and  posterior 
surfaces  ;  a  rough  prominence  about  its  middle,  the  internal 
tuberosity,  gives  insertion  to  the  teres  major  and  latissimus  dorsi 
miiscles.      The  medullary  foramen  is  in  its  inferior  third. 

The  proximal  extremity  presents  the  head  and  the  trochanters. 
The  head  is  convex,  and  considerably  larger  than  the  glenoid 
cavity  with  which  it  articulates,  allowing  extensive  and  varied 
motion  ;  it  is  surrounded  by  a  roughened  border  for  the  insertion 
of  the  capsular  ligament,  below  which  is  the  constricted  cervix  or 
neck  of  the  bone.  A  rough  depression  in  front  of  the  head 
contains  several  small  foramina  for  the  blood-vessels  which  supply 
the  cancellated  tissue  within. 

The  external  trochanter  has  two  prominences,  the  anterior,  or 
summit  of  the  trochanter,  which  forms  the  external  boundary  of 
the  bicipital  groove,  and  gives  insertion  to  the  outer  tendon  of 


HUMERUS.  69 

the  antea  spinatus  muscle,  while  the  posterior,  or  convexity  of  the 
trochanter,  the  more  prominent  of  the  two,  is  covered  with  fibro- 
cartilage,  over  which  glides  the  tendon  of  the  postea  spinatus- 
muscle,  which  is  inserted  to  a  rough  surface  below  the  convexity.. 
The  deltoid  ridge  joins  this  trochanter  to  the  external  tuberosity. 
The  internal  trochanter  is  divided  into  three  roughened  parts 
— anterior,  posterior,  and  inferior.  The  anterior  forms  the  internal 
boundary  of  the  bicipital  groove,  and  gives  insertion  to  the  inner 
tendon  of  the  antea  spinatus,  the  posterior  giving  attachment 
to  the  subscapularis,  and  the  inferior  to  the  pectoralis  magnus 
muscles.  Between  the  anterioi  part  of  the  internal  and  the 
summit  of  the  external  trochanters  is  the  bicipital  groove,  divided 
by  a  middle  prominence  into  two  channels,  the  whole  being 
covered  with  fibro-cartilage  ;  through  this  groove  the  tendon  o£ 
the  flexor  brachii  muscle  plays. 

The  distal  extremity  is  smaller  than  the  proximal,  and  smooth 
to  articulate  with  the  radius  and  ulna ;  its  surface  is  convex, 
and  wider  in  front  than  behind.  A  deep  groove,  which  extends 
from  the  coronoid  fossa  in  front,  terminating  in  the  condyloid  or 
olecranon  fossa  posteriorly,  divides  it  iato  an  internal  condyle^, 
and  an  external  condyle  or  trochlea,  the  latter  being  the  smaller^, 
and  having  a  shallow  furrow  running  across  it  from  before  back- 
wards. At  the  side  of  the  external  condyle  is  a  deep  pit  in 
which  the  external  lateral  ligament  is  attached,  and  from  which 
a  prominent  ridge,  the  epitrochlea,  extends  upwards  and  gives, 
origin  to  the  extensor  metacarpi  magnus,  extensor  pedis,  and. 
flexor  metacarpi  extemus  muscles. 

Running  upwards  from  the  posterior  part  of  the  internal 
condyle  is  a  large  eminence,  the  epicondyle,  from  which  the 
flexor  metacarpi  internus,  part  of  the  medius,  and  the  flexor  pedis- 
perforans  and  perforatus  muscles  arise,  and  on  its  side  is  a  small 
eminence  for  the  attachment  of  the  internal  lateral  ligament,  A 
deep  ovoid  fossa,  the  condyloid,  which  receives  the  olecranon 
process  of  the  ulna  during  the  extension  of  the  joint,  separates 
the  epicondyle  from  the  epitrochlea  posteriorly;  and  anteriorly, 
just  above  the  groove  in  the  articular  surface,  is  the  shallow 
coronoid  fossa,  which  receives  the  coronoid  process  of  the  radius 
during  extreme  flexion. 


70  OSTEOLOGY. 


TH'E   ^OREAKM. 


The  bones  of  the  forearm  are  the  radius  and  the  ulna,  which 
in  the  young  animal  are  distinct,  but  in  the  adult  become  firmly 
united  by  ossification,  and  are  sometimes  described  as  one  bone, 
the  OS  antibrachil      We  describe  them  separately. 


EADIUS, 
(Pl.  I.  L.) 

The  radius  is  a  long  bone,  and  occupies  a  vertical  position 
between  the  humerus  and  the  carpus.  The  shaft  is  flattened 
and  curved,  with  gradually  expanding  extremities  ;  its  anterior 
surface  is  smooth,  and  covered  in  the  fresh  state  by  the  extensor 
muscles  of  the  knee  and  foot ;  and  its  posterior  surface,  concave 
"from  above  downwards,  and  covered  by  the  flexor  muscles, 
presents  towards  its  external  border  a  rough  triangular  surface, 
which  commences  in  a  slender  point  near  the  middle  of  the  bone, 
and  terminates  two  or  three  inches  below  the  pl-oximal  end.  cor- 
responding with  the  anterior  surface  of  the  ulna,  to  which  it  is 
attached  by  interosseous  ligaments  in  the  young  animal,  and  by 
ossificati9n  in  the  adult.  The  shallow  transverse  groove  above 
this  surface  assists  in  the  formation  of  the  radio-ulnar  arch,  and 
the  nutrient  foramen  of  the  bone  is  close  to  the  groove.  On  the 
inferior  third  of  the  internal  border  of  the  shaft  is  a  ridge  to 
-which  the  radialis  accessorius  muscle  is  attached  ;  the  external  and 
internal  lateral  surfaces  are  rounded,  and  have  no  distinct  separa- 
tion from  the  anterior  and  posterior  surfaces. 

The  proximal  extremity,  larger  than  the  distal,  is  widest  from 
side  to  side,  and  presents  an  articular  surface,  divided  into  two 
depressions,  the  glenoid  cavities,  which  receive  the  condyles  of 
the  humerus  ;  the  inner  is  the  largest,  and  articulates  with  the 
internal  condyle,  the  outer  having  a  slight  eminence  on  its  centre 
which  corresponds  with  the  depression  in  the  trochlea.  A  rough 
ridge  round  the  articular  surface  gives  attachment  to  the  capsular 
ligament  ;  the  anterior  part  has  a  prominent  lip,  the  coronoid 
process,  in  its  centre,  and  near  its  internal  border  a  rough 
eminence,  the  bicipital  tuberosity,  for  the  insertion  of  the  tendon 
of  the  flexor  brachii,  and  part  of  the  humeralis  extemus  muscles. 
On  each  side  of  the  articular  surface  is  a  roughened  portion  for 


ULNA.  7 1 

the  lateral  ligament ;  the  external,  which  is  prominent  and  called 
the  external  tuberosity,  giving  origin  to  the  extensor  pedis  and 
extensor  suffraginis  muscles.  Posteriorly,  two  concave  facets 
articulate  with  the  ulna. 

The  distal  extremity,  like  the  proximal,  is  widest  from  side  to 
side;  its  articular  surface  is  divided  into  three  facets,  the  internal 
of  which,  the  largest,  and  quadrilateral  in  shape,  articulates  with 
the  scaphoid  bone ;  the  middle,  resembling  the  internal, but  smaller, 
articulates  with  the  lunar  bone  ;  and  the  external,  the  smallest, 
oval  in  shape  and  convex,  articulates  with  the  cuneiform  bone 
and  the  trapezium.  ■  The  whole  articular  surface  is  surrounded  by 
a  prominent  ridge  for  the  capsular  ligarrient.  The  anterior  part 
of  this  extremity  is  irregular,  and  has  two  deep  vertical  grooves 
for  the  tendons  of  the  extensor  muscles,  and  a  shallow,  oblique 
one,  in  which  the  tendon  of  the  extensor  metacarpi  obliquus 
muscle  plays.  Laterally,  two  prominent  processes,  the  internal 
being  the  largest,  give  attachment  to  the  lateral  ligaments  ;  the 
external  of  these  processes  is  grooved  for  the  passage  of  the 
extensor  suffraginis  tendon. 

ULNA. 
(Pl.  I.  L'.) 

The  ulna  is  an  irregular  bone,  in  form  triangular,  with  the  base 
uppermost,  and  is  placed  on  the  supero-posterior  part  of  the  radius. 
This  bone,  which  grows  but  little  after  birth,  is  larger  in  the 
young  animal,  proportionately  to  its  ultimate  size,  than  any  other 
bone.      It  possesses  a  body  and  two  extremities. 

The  body  is  triangular,  and  has  three  siTrfaces  and  three 
borders.  The  anterior  surface  is  the  counterpart  of  the  posterior 
surface  of  the  radius  against  which  it  is  applied,  having  superiorly 
two  convex  facets  to  articulate  with  the  concave  ones  o^i  the  head 
of  the  radius ;  below  these  is  a  rough  portion  for  the  attachment 
of  the  interosseous  ligaments,  and  still  lower,  a  shallow  transverse 
groove  which  assists  in  the  formation  of  the  radio-ulnar  arch, 
inferior  to  which  is  a  roughened  surface  for  the  attachment  of  the 
ligaments,  in  which  ossification  takes  place  in  the  adult  animal. 
The  external  surface  is  flattened  and  covered  by  the  flexor 
metacarpi  externus  muscle,  and  the  excavated  internal  face 
gives  attachment  to  the  ulnaris  accessorius,  and  is  covered  by 
the  flexor  pedis  muscles.      The  lateral  borders  are  thin,  and  have 


72 


OSTEOLOGY. 


tke  arciform  ligaments  attached,  and  the  'posterior  border,  concave 
and  round  gives  attachment  to  muscles. 

The  distal  extremity  is  pointed,  and  extends  a  little  below  the 
middle  of  the  radius,  though  sometimes,  in  the  ass  and  mule  par- 
ticularly, it  reaches  the  inferior  extremity  of  that  bone. 

The  'proxiTYial  extremity  comprises  that 
considerable  portion  of  the  bone,  corres- 
ponding to  the  elbow  of  man,  which  projects 
upwards  and  backwards  from  the  articular 
surface  of  the  radius,  and  is  known  as  the 
olecranon  i^rocess.  It  presents  two  sur- 
faces, two  borders,  and  a  summit.  The 
external  surface  is  slightly  convex,  and 
roughened  for  muscular  attachment;  the 
internal  surface  is  hollowed  and  smooth  ; 
the  posterior  border,  concave,  thin,  and 
smooth ;  and  the  anterior  border,  thin 
superiorly,  is  hollowed  into  a  crescent- 
shaped  surface,  which  articulates  with,  or 
rather  behind  and  between,  the  condyles  of 
the  humerus,  the  prominent  portion  being 
known  as  the  beak  of  the  olecranon.  The 
summit  is  the  broad  roughened  protuberance 
which  gives  insertion  to  the  tendon  of  the 
triceps  extensor  brachii  muscle,  tbe  olecranon 
being  the  lever  on  which  that  muscle  acts. 
It  is  important  to  note  that  the  development 
of  the  ulna  is  directly  proportional  to  the 
number  of  fingers  or  digits,  hence  the  horse, 
being  a  monodactyle,  has  a  very  short  ulna; 
compare  this  bone  in  the  ox  and  dog. 


Fig.  16. 
Front  aspect  of  the  right 
«arpus  of  a  Horse.  1,  Cunei- 
form ;  2,  Lunar ;  3,  Scaphoid ; 
4,  Trapezium  ;  5,  Unciform  ; 
6,  Magnum  ;  7,  Trapezoid  ; 
*  *,  Small  metacarpals,  the 
large  one  lying  between  and 
^before  them.  The  uppermost 
tone  is  the  distal  end  of  the 
xadius. 


CARPUS. 

The  carpus,  wrist,  or  knee,  as  it  is  incorrectly  termed  in 
quadrupeds,  is  composed  of  seven  and  often  of  eight  small, 
irregular  bones,  arranged  in  two  rows  of  three  each,  one  above 
the  other,  the  sevehth  being  at  the  back  of  the  three  in  the 
upper  row,  and  the  eighth,  when  present,  in  a  similar  position 
■with  respect  to  the  lower  row.  The  joints  between  them  pnss 
xjompletely  through  from  front  to  back,  and  are  so  arranged  that 


73 


i;hose  of  one  row  do  not  correspond  to 
Fig.  16.) 

It  may  be  noted  that,  virtually, 
continuous  articular  surfaces  are 
formed  by  tlie  bones,  by  wliicli  the 
upper  row  articulates  with  the  ra- 
dius, the  lower  with  the  metacarpus, 
and  the  two  rows  with  each  other. 
Each  bone  also  has  facets,  which  are 
often  deep-seated,  for  articulation 
with  contiguous  bones,  and  rough- 
ened depressions  between  the  facets 
for  the  attachment  of  ligaments. 
The  true  carpal  joint,  or  principal 
seat  of  motion,  is  between  the  radius 
and  the  upper  row ;  there  is  less 
motion  between  the  rows,  and  still 
less  between  the  lower  one  and  the 
metacarpus.  The  lesion,  termed 
"  broken  knees,"  usually  occurs 
where  there  is  the  most  extensive 
motion 

Naming  from  within  outwards, 
the  bones  of  the  upper  row  are  the 
scaphoid,  lunar,  and  cuneiform,  and 
the  trapezium  behind  the  latter; 
those  of  the  lower  row  are  the  trape- 
zoid, OS  magnum,  and  unciform  and 
the  pisiform  behind  the  trapezoid. 

fSCAPIiOID. 
(Fig.  16.    3.) 

The  scaphoid,  the  innermost  and 
largest  of  the  bones  of  the  upper  row, 
presents  six  surfaces,  the  anterior  and 
external  being  continuous,  convex,  and 
roughened  for  ligamentous  attachment; 
the  posterior  is  rough  and  irregular  ; 
and  the  internal,  excava,ted  8.nd 
roughened,  has  three  projections,  bear- 
ing facets  which  articulate  with  the 
lunar  bone.      The  superior  surface  is 


those  of  the  other.     (See 


Fig.  17. 
External  view  of  bones  of  right  car- 
pus, metacarpus,  and  digit  of  a  Horse. 
1,  Distal  end  of  radius  ;  2,  Grooves  for 
extensor  tendons ;  3,  Scaphoid  ;  4, 
Lunar ;  5,  Cuneiform  :  6,  Trapezium : 
7,  Magnum;  8,  Unciform;  9,  Great 
Metacarpal ;  10,  External  small  meta- 
carpal (splint) ;  11,  Sesamoids  ;  12, 
Proximal  phalanx  (os  suffraginis) ;  13, 
Median  phalanx  (os  coronas);  14,  Third 
sesamoid  (os  naviculare) ;  15,  Distal 
phalanx  (os  pedis) ;  16,  Basilar  pro- 


smooth,    concavo-convex. 


74  OSTEOLOGY. 

and  articulates  with  the  internal  part  of  the  distal  end  of  the 
radius ;  the  inferior  surface  is  also  smooth  and  articular,  con- 
sisting of  an  anterior  portion,  slightly  convex,  for  the  os  mag- 
num below,  and  a  posterior  concave  or  cup-shaped  one  for  the 
trapezoid. 

The  scaphoid  articulates  with  four  bones — viz.,  the  radius  above,, 
the  lunar  internally,  and  the  os  magnum  and  trapezoid  below. 


LUNAR  BONE. 
(Fig.  16.  2.) 

The  lunar  bone  (os  lunare),  the  middle  bone  of  the  upper 
row,  both  in  size  and  position,  is  somewhat  wedge-shaped, 
and  has  four  surfaces,  a  base,  and  an  apex.  The  superior 
surface  is  all  articular,  triangular  in  shape,  with  a  concavity 
posteriorly ;  it  articulates  with  the  middle  part  of  the  distal  end 
of  the  radius.  The  inferior  surface  is  articular,  and  divided  hj 
a  ridge  into  an  oblong,  concavo-convex  portion,  occupying  about 
five-sixths  of  the  surface,  and  articulating  with  the  os  magnum ; 
and  another  small,  oblong,  and  flat  part,,  situated  at  the  antero- 
external  border,  and  articulating  with  the  unciform  bone.  The 
internal  surface  is  excavated  and  roughened,  and  possesses 
three  articular  projections,  which  correspond  with  those  on  the 
scaphoid,  the  external  surface  having  two  for  the  cuneiform 
bone.  The  base  is  rough,  somewhat  trapezium-shaped,  and  is 
placed  anteriorly,  the  apex,  rough  and  tuberous,  being  directed 
backwards. 

The  lunar  articulates  with  five  bones — viz.,  the  radius  above, 
the  scaphoid  internally,  the  cimeiform  externally,  and  the  oS  mag- 
num and  unciform  below. 


CUNEIFORM  BONE. 
(Fig.  16.  1.) 

This  is  the  smallest  and  most  external  of  the  bones  of  the  upper 
row,  and  has  five  surfaces ;  the  superior,  which  is  cup-shaped, 
articulates  with  the  radius,  and  the  inferior,  somewhat  concave, 
with  the  unciform  bone.  The  external  surface  is  convex  and 
rough,  and  gives  attachment  to  ligaments,  while  the  internal 
has  two  facets  which  articulate  with  the  lunar;    the  posterior 


TRAPEZOID.  75 

surface,  whicli  slopes  downwards  and  backwards,  presents   on  its 
inferior  half  a  cup-shaped  articular  facet  for  the  trapezium. 

The  cuneiform  articulates  with  four  bones — viz.,  the  radius 
above,  the  lunar  internally,  the  unciform  below,  and  the  trape- 
zium behind. 

TRAPEZIUM.* 
(Fig.  16.  4.^ 

Placed  immediately  behind  the  cuneiform  bone,  the  trapezium 
is  broad  and  flattened,  and  presents  two  surfaces  and  a  cir- 
cumference. Both  its  surfaces  are  rough,  the  internal  being 
concave  and  the  exiernal  convex,  the  latter  having  a  deep 
groove  for  the  passage  of  one  of  the  tendons  of  the  flexor  meta- 
carpi  externus  muscle.  The  circumference  is  roughened,  the 
superior  part  receiving  the  insertion  of  the  tendon  of  the  flexor 
metacarpi  medius,  with  the  second  tendon  of  the  externus  muscles, 
while  the  remaining  portion  is  rough  for  ligamentous  attach- 
ment. Anteriorly  there  are  two  small  facets,  an  upper  concave 
one  to  articulate  with  the  radius,  and  a  lower  convex  one  articu- 
lating with  the  cuneiform  bone.  As  the  trapezium  is  the  lever 
bone  of  the  carpal  joint,  its  development  and  position  are  point* 
of  very  great  importance. 

TRAPEZOID 

(Fig.  16.  7.) 

This,  the  smallest  of  all  the  bones  of  the  carpus,  excepting  the 
pisiform,  is  placed  on  the  lower  row  on  the  inside ;  it  presents 
four  surfaces,  a  base,  and  an  apex.  The  superior  surface,  smooth 
and  rounded  from  before  backwards,  articulates  with  the  scaphoid. 
The  inferior  surface  is  smooth,  with  two  united  facets,  one  of 
which,  large,  flat,  and  semicircular,  articulates  with  the  inner 
metacarpal  bone,  and  the  other,  small,  square,  and  bevelled,  with 
the  great  metacarpal  bone.  The  internal  surface  is  convex  and 
rough,  and  the  external  rough,  with  the  exception  of  three  pro- 
jecting facets,  which  articulate  with  the  os  magnum.  The  apex  is 
placed  forwards,  and  the  base  backwards,  both  being  roughened  ; 
a  very  small,  cup-shaped  articulation  for  the  pisiform  bone  is 
often  found  on  the  posterior  part  of  the  base. 

The  trapezoid   articulates  with   five   bones — viz.,  the  scaphoid 

*  See  note  on  page  77. 


76  OSTEOLOGY. 

above,  the  magnum  internally,  tlie  large  and   inner  metacarpals 
below,  and  the  pisiform  postero-externally. 

OS  MAGNUM. 

(Fig.  16.  6.) 

The  OS  magnum,  the  largest  bone  in  the  carpus,  and  the 
central  one  in  the  lower  rovr.  is  somewhat  triangular  in  shape, 
and  presents  four  surfaces,  a  base,  and  an  apex.  The  su2)crior 
surface  is  divided  into  two  portions  by  a  ridge,  the  concave  inner 
part  articulating  with  the  scaphoid,  and  the  external,  which  is 
oblong  and  concavo-convex,  with  the  lunar  bone.  The  Inferior 
surface,  smooth  and  flat,  rests  on,  and  articulates  with  the  large 
metacarpal  bone,  having  also  a  very  small  bevelled  portion  near 
its  inner  surface,  which  articulates  with  the  mner  metacarpal 
bone.  The  internal  surface  is  rough  and  irregular,  and  has 
three  facets  which  articulate  with  the  trapezoid  :  the  extei^nal 
surface  joins  the  unciform,  having  two  facets.  The  hase  is 
placed  anteriorly,  it  and  the  apex  both  being  roughened  for 
ligamentous  attachments. 

The  OS  magnum  articulates  with  six  bones — viz.,  the  scaphoid 
and  lunar  above,  the  large  and  inner  small  metacarpals  below, 
the  trapezoid  internally,  and  the  unciform  externally. 

UNCIFORM  BONE. 
(Fig.  16.  5.) 

This,  the  external  bone  of  the  lower  row.  Is  very  iiTegular  in 
form,  and  somewhat  resembles  the  trapezoid  ;  it  has  four  surfaces, 
a  base,  and  an  apex.  The  stipe rior  surface,  convex  from  side 
to  side,  and  sloping  externally,  articulates  with  the  lunar 
and  cuneiform  bones.  The  'inferior  surface  articulates  by  two 
facets  with  the  large,  and  one  with  the  small  metacarpal  bone. 
The  internal  surface  presents  two  facets,  which  articulate  with 
the  OS  magnum.  The  external  surface  is  narrow ;  the  hase  is 
situated  anteriorly,  the  apex  being  the  prominent  unciform  pro- 
cess, and  aW  the  three  parts  are  roughened  for  ligamentous 
attachment. 

The  unciform  articulates  with  five  bones — viz.,  the  lunar  and 
cuneiform  above,  the  magnum  internally,  and  the  large  and 
external  metacarpals  below. 


OS    METACARPI    MAGNUM. 


77 


PISIFORM    BONE.* 

The  pisiform  is  a  very  small,  pea-shaped  bone,  situated,  when 
present,  at  the  postero-internal  part  of  the  knee,  in  some  cases 
articulating  with  the  trapezoid,  and  in  others  being  imbedded  in 
the  internal  lateral  ligament.  It  is  generally,  perhaps  always, 
present  in  old  subjects,  but  often  overlooked  owing  to  its  small 


METACARPUS. 

The  metacarpus,  that  part  of  the  skeleton  which  lies  between 
the  carpus  and  the  finger,  consists,  in  the  horse,  of  three  bones. 
The  principal  one,  the  great  metacarpal  bone,  situated  between 
the  others,  which  are  called  the  inner  and  outer  small  meta- 
carpals, is  the  only  perfect  one  of  the  three  ;   the  others  are  not 

D  C  K  A 


Fig.  is. 

Generic  development  of  the  Horse's  foot.     A,  Foot  of 

Eohippus  :  B,  That  of  Orohippus ;  C,  That  of  Hipparion  ; 

D,  That  of  Horse.   The  digits  are  numbered,  when  present, 

I.  to  V. 

only   small,   but  they  have   no    distal    articular  surface, 
frequently  all  three  bones  become  united  by  ossification. 


Very 


OS   METACARPI    MAGNUM. 
(Fig.  17.  9.) 

The  large  metacarpal,  or  cannon  bone,  is  a  long,  straight 
Tjone,  placed  in  u  vertical  direction.  This  bone,  one  of  the  most 
compact  in  the  skeleton,  is  flattened  in  its  shaft,  from  before  back- 
wards, especially  towards  its  distal  end,  the  anterior  surface  being 
convex  and  smooth,  and  the  posterior  broad,  flattened,  and  pierced 

*  [Some  authorities  call  this  bone  the  Trapezium,  and  oiir  Trapezium  the 
Pisiform.  Either  view  may  be  admissible,  as  the  nomenclature  will  depend 
upon  whether  we  compare  these  bones  analogously  or  homologously  with  those 
of  the  human  carpus. — Ed.,  Second  Edition.] 


78  OSTEOLOGY. 

at  about  one-third  from  the  top  by  the  raedullary  or  nutrient 
foramen.  On  each  side  of  this  surface  is  a  vertical  ridge,  to- 
which  the  small  metacarpals  are  attached. 

The  proximal  extremity  presents  a  smooth  surface,  formed  by 
three  continuous  articular  facets,  one  large  and  flat,  on  which 
the  OS  magnum  rests  ;  the  second,  very  small,  on  the  postero- 
internal border,  articulates  with  a  portion  of  the  trapezoid ;  and 
the  third,  which  articulates  with  the  unciform,  and  occupies  the 
whole  external  border,  is  bevelled  off  from  within  outwards,  and 
divided  by  a  deep  furrow  into  two  portions.  In  front  of  the 
large  articulation,  towards  the  intero-anterior  portion  of  the 
head,  is  a  roughened  prominence  for  the  insertion  of  the 
extensor  metacarpi  magnus  tendon :  and  at  the  posterior  part 
of  the  head  a  roughened  surface,  from  which  the  suspensory" 
and  check  ligaments  originate,  and  on  each  side  two  facets, 
divided  by  furrows,  articulate  with  the  small  metacarpal  bones. 

The  distal  extremity,  widest  from  side  to  side,  and  convex 
from  before  backwards,  presents  an  articular  surface,  consisting 
of  two  condyles  joined  by  a  prominent  semicircular  ridge,  the 
whole  of  which  articulates  with  the  os  suffraglnis  below,  and 
the  two  sesamoid  bones  behind.  Each  of  the  condyles,  the 
internal  being  slightly  the  larger  of  the  two.  presents  a  depression 
on  its  side  for  the  insertion  of  the  lateral  ligament.  Thus  the 
large  metacarpal  bone  articulates  superiorly  with  the  trapezoid, 
magnum,  and  unciform,  laterally  with  the  small  metacarpals,  and 
inferiorly  with  the  os  suffraginis  and  the  two  sesamoid  bones. 


OSSA    METACARPI    PARVA. 

(Fig.  17.  10.) 

The  small  metacarpal,  or  splint  bones,  tuberous  in  form  at  the 
carpus  and  tapering  distally,  are  attached  to  the  large  bone,  one 
on  each  side  of  its  posterior  surface,  by  ligaments  in  the  young 
animal,  and  by  ossification  in  most  grown  up,  and  in  all  old 
animals.  They  vary  somewhat  in  length  in  different  animals, 
but  are  usually  about  two-thirds  of  the  length  of  the  cannon,  the 
internal  being  generally  the  largest. 

The  base,  or  head,  of  each  bone  is  turned  upwards,  its  superior 
surface  being  articulatory,  and  assisting  to  form  the  carpal-joint. 
The  internal  one  possesses  two  a^-ticular  facets,  one  large  and  flat, 
on  which  the  trapezoid  rests,  and  the  other  small  and  bevelled 


DIGIT. 


79 


towards  its  anterior  surface,  to  articulate  with  a  portion  of  the 
OS  magnum,  while  the  external  splint  has  but  one  carpal  facet, 
which  gives  support  to  the  unciform  bone.  Below  the  articular 
surface,  externally,  the  heads  are  rough-  i 

ened  for  the  insertion  of  the  tendon  of 
the  flexor  metacarpi  intern  us  to  the  inner, 
and  that  of  the  flexor  metacarpi  externus 
to  the  outer.  The  head  of  each  of 
these  bones  presents  two  articular 
facets,  which  correspond  to  those  on  the 
sides  of  the  head  of  the  cannon  bone. 
The  middle  part  or  body  tapers  grad- 
ually downwards  from  the  head,  and  is 
firmly  attached  to  the  large  metacarpal 
bone  by  its  anterior  surface.  The  apex 
terminates  in  a  small  knob,  which  never, 
except  in  disease,  becomes  attached  to 
the  parent  bone.  These  knobs  are  very 
prominent  in  well-bred  horses,  and  are 
sometimes  mistaken  for  splints,  which  are 
exotoses  between  the  large  and  small 
metacarpal  bones. 


DIGIT. 

The  digit  or  finger  is  composed  of 
three  bones  placed  one  immediately  below 
the  other,  and  having  three  supplemen- 
tary or  sesamoid  bones  placed  behind. 
The  three  principal  bones  are  homolog- 
ous with  the  three  phalanges  of  the  human 
finger,  the  os  suffraginis  representing  the 
first  or  proximal,  the  os  coronas  the 
second  or  median,  and  the  os  pedis  the 
third  or  distal  phalanx. 

The  joint  which  the  large  metacarpal 
bone  forms  with  the  os  suffraginis  and 
its  two  sesamoids  is  the  fetlock -joint, 
that  between  the  os  suffraginis  and  the  os  coronse  is  the  pastern 
joint,  and  that  between  the  os  corona  and  the  os  pedis,  with  its 
sesamoid  or  navicular  bone,  is  the  coflBn  joint. 


D 
Fig.  19. 
Posterior  view  of  phalanges  of 
a  Horse  disartictilated.  A,  Os 
suffraginis  ;  B,  Os  coron®  ;  C,  Os 
pedis  ;  D,  Os  naviculare,  or  third 
sesamoid ;  1  1,  Glenoid  cavities, 
joinedby  the  groove,  2;  3,  Rough 
surface  forV-shapedsesamoidean 
ligament ;  4  4,  Condyles  articu- 
lating with  cavities,  5  5 ;  6  6,  Con- 
dyles of  coronse  articulating  with 
glenoid  cavities  of  pedal  bone, 
7  7  ;  8  8,  Pyramidal  process  ;  9  9, 
Basilar  processes  ;  10  10,  Retros- 
sal  processes  ;  11  11,  Articular 
surfaces  between  navicular  and 
pedal  bones;  12,  Surface  con- 
tinuous with  glenoid  cavities,  7  7 ; 
13,  Posterior  edge;  and  14  14, 
Extremities  for  lateral  ligaments 
of  navicular  bone. 


80 


OSTEOLOGY. 


PROXIMAL    PHALANX. 

(Fig.  19.  A.) 


The  first  pbalanx,  also  called  the  os  suffraginis,  or  large  pastern 
bone,  passes  obliquely  downwards  and  forwards,  and  articulates 
with  the  cannon  bone  above,  and  the  median  phalanx  below.  It 
belongs  to  the  class  of  long  bones. 

The  shaft,  which  is  very  short  and  slightly  flattened  from  before 
backwards,  has  an  anterior  surface  convex  and  smooth,  and  a 
posterior  surface  somewhat  flattened,  the  latter  presenting  two 
roughened  ridges,  in  the  form  of  a  triangle,  with  its  base  upwards, 
to  which  certain  of  the  sesamoidean  ligaments  are  attached. 

The  proximal  extremity,  the  larger  of  the  two,  presents  a 
semUunar-shaped  articular  surface,  convex  in  front,  and  consisting 
of  two  glenoid  cavities  for  the  condyles  of  the  cannon  bone,  and 
a  deep  connecting  groove  for  the  eminence  between  them  ; 
behind,  on  each  side,  is  a  roughened  tuberosity  for  the  attachment 
of  the  crucial  sesamoidean  ligaments.  The  distal  extremity,  much 
smaller  than  the  proximal,  presents  two  condyles  connected  by  a 
shallow  groove,  continuous  with  which,  posteriorly,  is  a  pit  or 
depression  into  which  fits  a  prominent  lip  on  the  posterior  part 
of  the  median  phalanx,  and  in  the  centre  of  the  front  there  is  a 
slight  eminence,  to  which  a  slip  of  the  tendon  of  the  extensor 
pedis  muscle  is  attached.  On  each  side  is  a  roughened  depression 
for  the  insertion  of  the  lateral  ligaments. 

GREAT    SESAMOID    BONES. 
(Fig.  17.  11.) 

These  bones,  two  in  number,  are  placed  side  by  side  at  the 
postero-inferior  part  of  the  metacarpus  and  postero-superior  part 
of  the  OS  suffraginis  ;  they  are  irregular  or  polyhedral  in  shape, 
having  smooth  and  concave  anterior  surfaces,  the  internal 
bevelled  edges  of  which-  form  a  groove  into  which  the  ridge 
at  the  distal  extremity  of  the  cannon  bone  is  received,  the 
concave  portions  articulating  with  the  condyles  of  that  bone. 
The  posterior  surfaces  when  in  situ  form  a  channel,  which  is 
covered  with  fibro-cartilage,  for  the  passage  of  the  flexor  tendons 
of  the  digit.  The  superior  extremity  or  apex  of  each  bone  is 
roughened,  as  are  also  their  lateral  borders,  which  are  grooved  for 


DISTAL    PHALANX.  81 

the  reception  of  the  suspensory  ligament.  The  inferior  surface 
or  base  is  also  roughened,  to  afford  attachment  to  the  ligaments 
by  which  these  bones  are  attached  to  the  phalanges  below. 


MEDIAN    PHALAKX. 
(Fig.  19.  B.) 

The  second  phalanx,  os  coronee,  or  small  pastern  bone,  has  no 
medullary  canal,  and  belongs  to .  the  class  of  irregular  bones. 
It  is  inclined,  like  the  os  suffraginis,  obliquely  downwards 
and  forv^ards,  and  is  partly  covered  by  the  hoof  The  supenor 
surface  is  smooth,  and  divided  by  an  eminence  into  two 
glenoid  cavities  for  the  condyles  of  the  os  suffraginis,  and  having 
in  the  centre  two  slight  eminences,  one  in  front  and  one  behind, 
which,  by  limiting  its  motion,  make  the  joint  more  secure  ;  a 
portion  of  the  tendon  of  the  extensor  pedis  muscle  is  attached 
to  the  anterior,  and  a  ligament  to  the  posterior  of  these 
eminences.  The  inferior  suiface  of  the  bone  is  smooth  and 
convex,  and  divided  by  a  central  depression  into  two  condyles, 
which  articulate  with  the  os  pedis  and  os  naviculare.  The 
anterior  surface  is  convex,  very  rough,  and  widest  superiorly; 
it  affords  attachment  to  part  of  the  tendon  of  the  extensor  pedis 
muscle.  The  posterior  surf  nee,  slightly  excavated  and  not  very 
rough,  has  on  its  upper  part  a  prominent  eminence  covered  by 
fibro-cartilage,  over  which  plays  the  tendon  of  the  flexor  perforans, 
while  on  either  side  of  this  eminence  is  inserted  part  of  the 
tendon  of  the  flexor  perforatus  muscle. 

DISTAL    PHALANX. 

(Fig.  19.  C.) 

The  third,  or  ungual  phalanx,  os  pedis,  or  coffin  bone,  is  an 
irregular  bone  situated  within  the  hoof,  and,  when  in  a  healthy 
state,  corresponding  somewhat  to  it  in  shape,  being  semilunar  in 
form,  with  the  convexity  to  the  front.  It  is  a  very  hard  but 
porous  bone,  having  many  excavations  and  foramina  for  the 
transmission  of  arteries  and  veins.  In  this  bone  we  notice  the 
wall,  the  sole,  the  tendinous  surface,  the  articular  surface,  and 
the  alse  or  wings. 

The  wall^  or  anterior  surface,  is  the  semicircular  part  in  front 

G 


«2 


OSTEOLOGY. 


which  presents  numerous  depressions  and  foramina,  the  latter 
being  for  the  passage  of  blood-vessels  and  nerves,  and  the  former 
for  the  attachment  of  soft  structures.  Anteriorly  it  is  surmounted 
by  the  coronal  or  ^pyramided  process,  which  gives  insertion  to 
the  tendon  of  the  extensor  pedis  muscle,  and  prevents  the  os 
coronse  from  slipping  too  far  forwards ;  a  ligament  is  inserted  in , 
an  excavation  on  each  side  of  this  process.  The  inferior  edge  of 
the  wall  is  serrated  or  notched,  the  notches  opening  into  various 
foramina  ;  and  its  declivity  increases  in  degree,  but  decreases  in 
extent  as  it  proceeds  backwards.  At  each  side  is  the  preplayitar 
(/voovr,  which  terminates  posteriorly  in  the  large  foramen  of  the 
same  name,  and  along  which  the  lateral  laminal  artery  passes. 

The  sole,  or  inferior  surface,  which  lies  on  the  sensitive  or 
vascular  sole,  is  slightly  excavated  and  half-moon  shaped,  and, 
excepting  the  articular  surface,  is  the  smoothest  part  of  the 
bone ;  it  is  bounded  externally  by  the  inferior  edge  of  the  wall, 
and  at  its  postero-internal  part  by  an  uneven  semicircular  ridge, 
the  snnilunar  ridge,  which  separates  it  from  the  tendinous 
surface. 

The  tendinous  surface  is  the  roughened  portion  placed  imme- 
diately behind  the  sole  ;  it  presents  a  triangular  roughened 
depression  on  its  middle  and  anterior  part,  where  the  tendon  of 
the  flexor  pedis  perforans  muscle  becomes  inserted,  and  on  each 
side  a  groove,  the  plantar  groove,  which  terminates  in  the  large 
plantar  foramen  along  which  passes  the  artery  and  nerve  pro- 
ceeding to  the  interior  of  the  bone.  The  posterior  part  of  this 
surface  is  roughened  for  the  attachment  of  the  inferior  navicular 
ligament.  The  articular  surface  presents  two  glenoid  cavities, 
separated  by  a  slight  eminence  which  terminates  in  the  coronal 
process;  this  part  of  the  surface  articulates  with  the  inferior 
extremity  of  the  os  coronje.  Behind  the  cavities,  a  flattened, 
narrow  triangular  surface  articulates  with  the  os  naviculare. 

The  aloe,  or  ivings,  are  the  irregular  protuberances  on  the 
posterior  part  of  the  wall ;  they  are  bifid,  being  divided  by  a 
fissure  or  notch,  the  preplantar  fissure,  which  in  old  animals  is 
converted  into  the  preplantar  foramen,  through  which  the  lateral 
laminal  artery  passes  to  gain  the  groove  on  the  wall.  The 
inferior  and  posterior  portion  of  the  ala,  the  more  bulky  of 
the  two,  is  the  retrossal  process ;  and  the  superior  portion,  thin, 
and  giving  attachment  to  the  lateral  cartilage,  is  the  hasilar 
process 


PELVIC    ARCH.  83 

OS    NAVICULARE. 
(Fig.  19.  D.) 

The  navicular,  third  sesamoid,  or  shuttle  bone,  is  an  irreg- 
"ular  bone,  situated  with  its  long  axis  transversely,  behind  and 
below  the  os  coronas,  and  behind  the  os  pedis,  with  both  of  which 
it  articulates,  the  articulation  of  the  three  forming  the  so-called 
4iofin  joint.  The  superior  surface  is  smooth,  with  two  concavities 
and  a  central  eminence,  which  complete  the  articular  surface  for 
the  condyles  of  the  os  coronse  ;  the  inferior  surface  is  rather 
rough,  and  also  has  two  concavities  and  a  central  projection, 
which  are  covered  with  fibro-cartilage,  and  together  form  a  kind 
of  pulley  over  which  plays  the  tendon  of  the  flexor  perforans 
muscle.  The  anterior  border  is  divided  into  two  portions,  a 
superior,  smooth  and  triangular,  which  articulates  with  the  os 
pedis,  and  an  inferior,  elongated,  rough,  and  porous,  and  attached 
to  the  same  bone  by  the  inferior  navicular  ligament.  The 
posterior  border  is  triangular,  rough,  and  porous,  and  gives 
insertion  to  the  superior  ligament;  the  extremities  are  pointed, 
and  attached  to  the  alse  of  the  os  pedis  by  lateral  ligaments. 

Pelvic  Auch. 

The  posterior  extremity  is  united  to  the  trunk  by  the  direcV 
articulation  of  the  pelvic  arch  with  the  femur  and  sacral  vertebrae. 
The  three  bones  which  form  the  arch  become  early  united  by 
ossification,  and  the  entire  arch  is  called  the  os  innominatum. 
The  two  ossa  innominata  articulate  with  each  other  in  tbe  inferior 
median  line,  and  at  a  later  period  this  union  becomes  also  ossified; 
the  complete  structure  is  called  the  pelvis,  and  the  space  which 
it  helps  to  enclose  is  the  pelvic  cavity.  On  examining  the  pelvis 
in  situ,  we  find  that  the  anterior  portion  bounds  superiorly  a 
space  which  has  no  bony  floor ;  this  portion  has  been  termed  the 
Palse  Pelvis,  the  True  Pelvis  being  the  posterior  part  which,  by 
Tinion  of  its  right  and  left  segments,  forms  the  floor  of  the  cavity. 
Each  side  of  the  floor  is  pierced  by  a  very  large  opening,  the 
obturator  foramen,  or  foramen  ovale. 

The|3e7v/c  cavity  tlierefore  is,  in  the  skeleton,  included  between 
the  sacrum,  part  of  the  coccyx,  and  the  two  ossa  innominata. 
The  pelvis  is  always  much  smaller  proportionally  in  the  lower 


84  OSTEOLOGY. 

animals  than  in  man.  where,  especially  in  the  female,  it  is  large 
and  well  developed,  possessing  that  peculiar  basin-like  form 
identified  with  an  erect  posture  of  body.  We  have  already 
described  the  sacrum  and  coccyx,  and  have  now  to  describe  the 
ossa  innominata.  or  right  and  left  segments  of  the  pelvis. 


OSSA    INNOMINATA. 

The  ossa  innominata  are  flat,  but  somewhat  irregularly-shaped 
bones,  which  form  the  sides,  floor,  and  part  of  the  roof  of  the 
pelvic  cavity.  Above  they  are  connected  with  the  sacrum,  and 
below  united  to  each  other  in  the  adult  by  cccification.  In  the 
young  animal,  as  above  stated,  and  especially  in  the  foetus,  each 
OS  innominatum  consists  of  three  parts,  which  retain  their  names 
of  ilium,  ischium,  and  pubis,  even  after  union  by  ossification. 
They  all  three  meet  in  'Jie  ctcetabulura.  or  articular  cavity  tor  the 
femur. 

ILIUM. 

(PL.    I.    U.) 

The  ilium,  the  largest  and  most  symmetrical  bone  of  the  three, 
and  situated  partly  upon  the  sacrum  with  which  it  articulates, 
is  flat  and  irregularly-triangular  in  shape,  its  extreme  outer  angle 
being  one  of  the  most  prominent  points  of  the  animal,  forming 
the  projection  commonly  called  the  "  point  of  the  hip."  It  presents 
for  consideration  two  surfaces,  three  borders,  and  three  angles  or 
processes. 

The  eccternal  surface  is  concave  at  its  upper  part,  and  marked 
by  elevated  lines  for  the  attachment  of  the  gluteus  maximus 
muscle  ;  lower  down  it  becomes  convex  and  narrow,  forming  the 
upper  part  of  the  shaft  of  the  ilium,  which  is  three-sided.  As  it 
approaches  the  acetabulum  the  shaft  again  slightly  expands,  and 
becomes  roughened  for  the  attachment  of  the  gluteus  internus 
and  outer  head  of  the  rectus  femoris  muscles.  This  surface 
terminates  in  an  obtuse  angle,  the  outer  side  of  which  forms  a 
strong  anterior  margin  for  the  acetabulum ;  and  the  inner  side, 
surmounting  this  cavity,  marks  the  line  of  junction  between  the 
ilium  and  the  ischium. 

The  internal  or  venter  surface  is  slightly  convex,  its  upper 
portion  consisting  of  two  parts — an  outer  smooth  one,  correspond- 
ing to  the  iliac  fossa  in  man ;   and  an  inner,  which  rests  on  the>^ 


ILIUM.  85 

sacrum,  and  gives  attachment  to  the  inferior  sacro-iliac  ligament. 
The  iliacus  muscle  is  attached  to  the  venter  surface.  On  the 
lower  portion  is  a  line  or  ridge  continuous  with  the  anterior  edge 
or  brim  of  the  pubis ;  together  these  form  the  ilio-pectineal  line, 
which  inferiorly  separates  the  true  pelvis  from  the  false.  On  the 
inferior  border  of  the  shaft  is  the  nutrient  foramen,  and  in  front 
of  the  acetabulum  a  second  depression  for  the  inner  head  of  the 
rectus  feraoris  muscle.  Below  this  depression  is  the  ilio-pectineal 
eminence,  which  marks  the  junction  of  the  ilium  and  the  pubis, 
and  gives  attachment  to  the  psoas  parvus  muscle.  The  inner 
part  is  smooth,  concave,  and  grooved  backwards  and  downwards 
for  the  obturator  vessels 


Fia.  20. 

Left  poatero-lateral  view  of  a  Horse's  pelvis.  1,  Anterior  iliac  spine  ;  2, 
Posterior  iliac  spine.  The  iliac  crest  is  the  border  joining  1  and  2  ;  3,  niac 
shaft ;  4,  The  acetabulum,  the  large  rough  ridge  above  is  the  sciatic  spine  ; 
6,  Inferior  ischiatic  spine,  posterior  to  which  is  the  tuberosity. 

The  anterior  border,  or  crest  of  the  ilium,  lies  above  the  sacral 
transverse  process.  It  is  concave  above,  convex  below,  thin  in 
its  middle,  and  roughened  for  the  attachment  of  the  longissimus 
dorsi  and  other  muscles.  Internally  it  terminates  in  a  rounded 
eminence,  the  posterior  iliac  spine,  which  rises  above  the  last 
lumbar  and  first  sacral  spines,  and  forms  the  highest  part  of  the 
croup.  Externally  and  anteriorly  it  terminates  in  the  anterior 
iliac  spine,  which  consists  of  four  eminenges,  two  superior  and 
two  inferior,  supported  on  a  thick,  strong,  projecting  bony  plate ; 
these  eminences  give  attachment  to  the  oblique  and  transverse 


86  OSTEOLOGY. 

abdominal  and  other  muscles ;  they  are  more  developed  in  some 
horses  than  in  others,  and  occasionally  project  so  far  as  to  form, 
what  are  termed  "  ragged  hips." 

The  superior  or  internal  border  extends'  from  the  posterior 
spine  to  the  ischium.  It  is  sharp  and  thin  above,  and  becomes 
thicker  posteriorly,  presenting  above  the  acetabulum  a  roughened 
ridge,  the  sciatic  or  superior  ischiatic  spine,  the  posterior  por- 
tion of  which  is  formed  by  the  ischium,  and  to  which  a  large 
part  of  the  sacro-sciatic  ligament  is  attached. 

ISCHIUM. 

(PL.  I.  14.) 

The  ischium,  intermediate  in  size  between  the  ilium  and  the 
pubis,  is  a  flat,  irregularly  quadrilateral  bone,  which  extends 
from  the  acetabulum,  and  forms  the  posterior  part  of  the  pelvis  ; 
it  presents  a  body,  a  shaft,  and  a  ramus. 

The  shaft,  which  forms  part  of  the  sciatic  spine,  also  joins  the 
ilium  in  the  acetabulum;  it  is  rounded,  and  below  the  spine  has 
a  smooth  surface  over  which  the  obturator  intemus  and  pyri- 
formis  tendons  pass.  It  forms  the  external  boundary  of  the 
obturator  foramen. 

The  body,  which  is  nearly  horizontal,  is  flat  and  smooth,  and 
forms  the  posterior  boundary  of  the  obturator  foramen.  Inter- 
nally, it  is  roughened,  and  joins  its  fellow  of  the  opposite  side, 
forming  the  symphysis  ischii ;  posteriorly  it  is  roughened  for  the 
attachment  of  muscles,  and  possesses  on  its  external  part  a 
prominent  projection,  the  tuberosity  of  the  ischium,  to  which 
several  muscles  are  attached.  The  ridge  or  spin^  below,  running 
forwards  from  the  tuberosity,  is  the  inferior  ischiatic  spine, 
■while  the  posterior  border  of  the  bone  is  formed  by  a  thick  ridge 
running  from  the  tuberosity  to  the  symphysis,  forming  with  its 
fellow  the  ischial  arch,  which,  in  the  male,  supports  the  crura  of 
the  penis.  The  ramus,  not  well  developed  in  the  horse,  is  the 
small  branch  which  joins  the  pubis,  and  forms  part  of  the  inter- 
nal boundary  of  the  obdurator  foramen,  the  union  between  the 
bones  being  usually  marked  by  a  transverse  ridge. 

PUBIS. 

The  pubis,  which  is  the  smallest  division  of  the  os  innomiu- 
atum,  is  likewise  irregular  in  shape,  and  forms  with  its  fellow  the 


PELVIC    APERTURES.  87 

antero-inferior  part  of  the  pelvis ;   it  consists  of  a  body  and  a 
ramus. 

The  hody  reaches  from  the  acetabulum  to  the  median  sym- 
physis ;  its  superior  surface  is  concave  to  receive  the  urinary 
bladder,  and  its  inferior  surface  is  convex,  and  transversely 
crossed  by  a  deep  groove  from  the  acetabulum,  which  contains 
the  pubio-femoral  ligament.  The  crest  is  the  roughened  anterior 
border,  which  terminates  at  the  symphysis.  The  posterior  border 
extends  to  the  ramus,  and  forms  the  anterior  margin  of  the 
obturator  foramen ;  at  its  junction  with  the  ilium  it  is  crossed 
by  a  groove  for  the  obturator  vessels.  The  outer  extremity, 
which  joins  the  ilium  and  the  ischium  in  the  acetabulum,  is 
excavated  to  form  the  cotyloid  notch.  The  ramus  is  the  flattened 
portion  which  projects  posteriorly,  joins  the  ramus  of  the  ischium, 
forming  part  of  the  boundary  of  the  obturator  foramen,  and 
with  its  fellow  the  symphysis  pubis  internally. 

ACETABULUM. 

(Fig.  20.  4.) 

The  cotyloid  cavity  or  acetahulura  is  situated  on  the  extero- 
lateral  aspect  of  the  pelvis,  where  the  three  segments  of  the  os 
innominatum  unite.  It  receives  the  head  of  the  thigh-bone,  andl 
is  one  of  the  deepest  articular  depressions  in  the  body,  though 
relatively  it  is  much  less  capacious  in  -the  horse  and  in  quadru- 
peds generally  than  in  man.  It  is  circular  in  outline,  and, 
except  at  its  inferior  median  part,  is  surrounded'  by  a  prominent 
lip  of  bone,  which  becomes  thin  and  slightly  roughened  at  its 
free  surface  for  muscular  and  ligamentous  attachment;  its  mferior 
border  presents  a  large  notch,  the  cotyloid  notch,  continued 
half-way  across  the  articulation  as  the  fundus  acetahuli,  to  give 
attachment  to  the  round  ligament  (ligamentum  teres),  which 
mainly  occupies  it.  Although  the  cotyloid  cavity  is  formed  by 
the  three  segments  of  the  os  innominatum,  the  ilium  and  the 
ischium  are  generally  the  only  parts  which  form  its  articular 
surface,  the  pubis  in  most  cases  merely  helping  to  form  the 
roughened  notch  and  fundus. 

PELVIC   APERTURES. 

The  obturator  or  thyroid  foramen,  or  foramen  ovale,  the 
largest  foramen  in  the  body,  exists  in  each  os  innominatum,  and 


88  OSTEOLOGY. 

is  oval  in  outline,  its  long  diameter  being  directed  downwards, 
backwards,  and  inwards.  It  is  formed  entirely  by  the  pubis  and 
ischium,  and  possesses  smooth  margins,  and  thick,  except  where 
they  are  formed  by  the  pubis. 

The  inlet,  or  brim  of  the  pelvis,  is  bounded  superiorly  by 
the  sacral  promontory,  laterally  by  the  ilio-pectineal  line,  and 
inferiorly  by  the  crest  and  symphysis  of  the  pubis.  The  aper- 
ture thus  defined  inclines  downwards  and  backwards,  being 
somewhat  ovoid  in  form.  The  diameters  of  the  inlet  vary 
according  to  the  age  and  sex  of  the  animal ;  in  the  adult  male, 
the  verticle  or  sacro-pubic  diameter  is  a  little  less  than  the 
trausverse. 

The  outlet,  or  posterior  aperture,  is  somewhat  triangular  in 
form,  and  is  bounded  above,  at  its  apex,  by  the  first  coccygeal 
bone,  laterally  by  the  sacro-sciatic  ligaments,  and  inferiorly,  by 
the  ischia  and  ischiatic  spines.  Its  vertical  diameter,  from  the 
last  sacral  or  first  coccygeal  segment,  to  the  ischiatic  symphysis, 
is  less  than  the  transverse,  taken  between  the  ischiatic  spines. 
The  length,  taken  from  the  middle  of  the  lateral  part  of  the  inlet 
to  the  ischiatic  tuberosity,  is  usually  about  equal  to  the  transverse 
diameter  of  the  inlet. 

FEMALE   PELVIS. 

The  size  and  proportions  of  the  pelvis  differ  considerably  with 
the  sex  of  the  animal.  Bearing  in  mind  that  we  have  referred 
hitherto  to  the  pelvis  of  the  adult  male,  the  differences  in  that 
of  the  female  may  be  thus  summarised  : — ^The  whole  structure 
is  larger.  The  transverse  diameters  above  named,  in  fact,  the 
transverse  measurements  generally,  are  very  large,  the  former 
exceeding  the  vertical  diameters  by  a  mu^h  larger  difference 
than  is  found  in  the  male.  The  internal  border  of  the  ilium  is 
more  hollowed  out,  and  smoother.  The  ischial  arch  is  large,  and 
it  presents  a  concave  border,  tending  but  slightly  to  form  an 
angle  at  the  symphysis.  The  cotyloid  cavities  are  wider  apart 
than  in  the  male,  while  the  obturator  foramina  are  larger  and 
more  circular  in  form. 

PELVIC    LIMB. 

The  bones  of  the  pelvic  or  hind  extremity  are  the  femur, 
patella,  tibia,  and  fibula ;  the  bones  of  the  tarsus — viz.,  the 
astragalus,  os  calcis,  cuboid  and  three  cuneiform  bones ;  one 
large  and  two  small  metatarsals;  three  phalanges  and  three 
sesamoids.     See  p.  65. 


FEMUR. 


89 


FEMUR. 


(Fig.  21.) 

The  OS  feinoris,  femur,  or  thigh  bone,  the  largest,  thickest, 
-and  strongest  bone  in  the  body,  belongs  to 
the  class  of  long  or  cylindrical  bones,  and 
is  placed  in  a  direction  obliquely  down- 
wards and  forwards,  articulating  with  the 
cotyloid  cavity  of  the  os  innominatura,  and 
also  with  the  tibia  and  patella. 

The  shaft  is  irregularly  cylindrical,  and 
has  two  surfaces  and  two  borders.  The 
anterior  surface  is  smooth,  prominent,  and 
marked  by  a  few  muscular  imprints.  The 
posterior  surface  is  flattened  and  expanded 
at  its  upper  part,  and  presents,  towards  the 
external  part  of  its  upper  third,  a  circular 
roughened  surface  for  the  insertion  of  part 
of  the  triceps  abductor  muscle;  internal 
to  which  a  slight  ridge  runs  obliquely  up- 
wards and  inwards  to  join  the  internal 
trochanter,  to  this  the  ischio-femoralis  muscle 
is  inserted.  About  its  middle  third  is  a 
roughened  surface,  for  the  attachment  of  the 
adductor  brevis  and  part  of  the  adductor 
longus  muscles.  The  external  border,  which 
separates  the  anterior  from  the  posterior 
surface,  presents  a  prominent  ridge,  on  the 
upper  third  of  which  is  a  sharp,  flat  pro- 
tuberance, the  trochanter  minor,  curved 
forwards,  and  affording  attachment  to  the 
gluteus  externus  and  vastus  externus  muscles. 
At  the  lower  third  of  this  border  is  a  deep, 
oval,  roughened  pit,  the  supra- condyloid 
fossa,  from  which  the  flexor  perforatus 
muscle  arises ;  and  about  level  with  this, 

towards  the  inner  side,  is  an  aggregation  of  tubercles  forming 
the  supra-condyloid  crest,  where  arises  one  portion  of  the  gastro- 
cnemius muscle.  The  internal  border,  dividing  the  anterior  from 
the  posterior  surface  internally,  presents  near  its  upper  third 


Fio.  21. 
Posterior  view  of  left  femur 
of  a  Horse.  1,  Head  ;  2,  Tro- 
chanter major ;  3,  Trochanter 
minor  ;  4,  Trochanter  in  temus: 
5,  Notch  for  the  round  liga- 
ment ;  6,  Trochanteric  fossa  ; 
7,  8,  Places  of  attachment  for 
the  lateral  ligaments  ;  11,  The 
condyles,  separated  by  the 
intercondyloid  groove ;  10, 
Supra-condyloid  fossa. 


90  OSTEOLOGY. 

a  blunt  roughened  prominence,  the  trochanter  internus.  from 
which  a  ridge  extends  upwards  to  the  head,  and  to  which  the 
psoas  magnus,  iliacus,.  and  vastus  internus  muscles  are  attached. 
From  this  trochanter  another  ridge,  to  which  the  pectineus  muscle 
is  inserted,  runs  downwards,  the  nutrient  foramen  being  in  its. 
lower  part. 

The  proximal  extremity  terminates  in  the  head  and  the 
trochanter  major.  The  head  is  the  smooth  articular  portion 
directed  upwards  and  inwards,  and  is  received  in  the  cotyloid 
cavity  ;  it  is  separated  from  the  body  by  a  constricted  portion, 
the  neck,  not  well  marked  in  solipedes,  and  between  the  head 
and  neck  there  is  a-  ridge  for  the  attachment  of  the  capsular 
ligament.  The  deep  notch  at  the  inner  part  of  the  head  is  for 
the  attachment  of  the  pubio-femoral  and  round  ligaments.  The 
trochanter  major  is  a  very  large  eminence,  which  projects  out- 
wards and  upwards,  and  presents  posteriorly  a  prominent  part 
termed  the  summit,  wLich  stands  a  little  higher  than  the  arti- 
cular head,  and  gives  attachment  to  one  portion  of  the  gluteus 
maximus  muscle,  and  anteriorly  the  convexity,  which  is  rounded 
and  covered  externally  by  cartilage,  over  which  plays  another 
tendon  of  the  gluteus  maximus,  and  becomes  inserted  to  the 
ridge  just  below.  Behind  the  trochanter,  and  between  it  and 
the  head,  is  the  trochanteric  or  digital  fossa,  around  and  in 
which  several  small  muscles  are  inserted ;  bounding  this  fossa, 
externally  is  the  trochanteric  ridge,  continuous  with  the  posterior 
part  of  the  summit  of  the  trochanter. 

The  distal  extremity  presents  posteriorly  two  condyles,  and 
anteriorly  a  trochlea ;  the  condyles,  which  articulate  with  the 
head  of  the  tibia,  are  placed  side  by  side,  being  separated  by  a 
deep  intercondyloid  groove,  from  which  the  interosseous  crucial 
ligaments  of  the  articulation  spring,  and  into  which  the  spine  of 
the  tibia  projects.  The  external  condyle  has  two  fossae  on  the 
outside,  one  for  the  origin  of  the  popliteus,  and  one  for  the 
external  lateral  ligament;  the  internal  condyle  has  a  roughened 
prominence  on  its  lateral  surface,  for  the  attachment  of  the 
internal  lateral  ligament,  the  adductor  magnus,  and  part  of  the 
adductor  longus  miiscles. 

The  trochlea  is  the  pulley-shaped  part  to  the  front  of  the 
condyles,  which  articulates  with  the  patella ;  it  consists  of  two 
prominences  divided  by  a  groove,  and  it  is  in  a  line  with  the 
intercondyloid   fossa.      The  internal  prominence  is  the  thickest 


TIBIA.  ,  91 

and  most  pronounced,  and  on  the  side  of  the  bone,  between  the 
external  prominence  and  the  external  condyle,  is  a  depression,  in 
which  the  tendons  of  origin  of  the  extensor  pedis  and  flexor 
metatarsi  muscles  are  attached. 

PATELLA. 
(Pt.  I.  X.) 

This,  the  knee-pan  or  stifle  boue,  is  placed^  in  front  of  the 
trochlea  of  the  femur.  It  is  very  compact,  its  anterior  surface 
being  irregularly  convex  and  very  much  roughened,  for  liga- 
mentous attachment,  and  its  posterior  surface  smooth  to  articu- 
late with  the  trochlea  of  the  femur,  presenting  two  concavities 
divided  by  a  ridge,  the  innermost  being  the  larger,  and  in  the 
fresh  state  enlarged  still  more  by  a  projecting  fibro-cartilaginous 
lip,  or  process.  The  superior  surface  of  this  bone  is  broad, 
uneven',  and  roughened,  giving  insertion  to  the  group  of  muscles 
called  the  triceps  (or  quadriceps)  cruralis ;  the  inferior  smface  is 
rough  and  pointed,  and  gives  attachment  to  the  middle  straight 
ligament  of  the  patella,  while  the  lateral  borders  and  angles  have 
the  externa]  and  internal  straight  ligaments  attached. 

The  patella  is  the  lever  bone  of  the  stifle  joint,  or  it  may  be 
regarded  as  a  sesamoid  bone,  developed  in  the  tendons  of  the 
attached  muscles,  so  as  to  increase  their  power,  enabling  them 
to  act  at  an  advantageous  angle.  It  is  liable  to  fracture  by 
muscular  contraction,  and  to  luxation  ;  in  the  latter  case  the 
internal  lateral  ligament  is  injured,  or  may  by  ruptured. 

TIBIA. 
(PL.  I.  Y.) 

The  tibia,  or  leg  bone,  is  a  long  bone,  larger  at  its  proximal 
than  its  distal  end,  situated  between  the  femur  and  the  astra- 
galus, slanting  downwards  and  backwards. 

The  shaft  is  three-sided,  possessing  outer,  inner,  and  posterior 
surfaces,  all  of  which  are  wider  above  than  below.  The  outer 
surface,  concave  superiorly  and  convex  inferior ly,  is  smooth,  and 
lodges  the  extensor  pedis  muscle ;  the  inner  surface,  slightly 
convex  from  side  to  side,  is  smooth,  excepting  at  its  superior  part, 
where  it  gives  attachment  to  one  tendon  of  the  biceps  rotator 
tibialis,  the  sartorius  and  gracilis  muscles,  and  is  covered  chiefly 
by  skin,  fascia,  and  a  strong  periosteum.      The  posterior  surface 


9  2  OSTEOLOGY. 

the  broadest  of  the  three,  presents  on  its  superior  third  a 
triangular  and  rather  smooth  portion,  to  which  the  popliteus 
muscle  is  attached,  the  remaining  two-thirds  being  strongly- 
marked  by  a  number  of  longitudinal  ridges,  and  giving  attach- 
ment to  the  deep  flexor  muscles  of  the  foot  ;  the  nutrient 
foramen  is  in  the  upper  third  of  this  surface. 

The  anterior  border  is  rounded,  and  indistinctly  marked, 
except  in  its  upper  third,  where  we  find  the  prominent  tibial 
ridge,  which  is  curved  outwards,  and  joins  the  anterior 
tuberosity  of  the  proximal  extremity.  The  external  border  is 
thick  and  concave  above,  so  that  with  the  fibula  it  forms  the 
tibial  arch.  The  internal  border  is  also  thick,  and  at  its  upper 
part  has  a  small  tubercle,  to  which  the  popliteus  muscle  is 
attached. 

The  proximal  extremity  is-'  much  more  •  expanded  than  the 
distal,  and  presents  two  large,  smooth,  somewhat  .  undulated, 
articular  surfaces,  divided  by  a  roughened  conical  process,  the 
tibial  spine,  on  the  outer  side  of  which  is  an  irregular  excava- 
tion for  the  insertion  of  one  of  the  crucial  ligaments.  The  semi- 
lunar cartilages  are  interposed  between  these  surfaces  and  the 
condyles  of  the  femur.  Anteriorly  a  tuberosity,  concave  exter- 
nally and  convex  internally,  joins  the  tibial  ridge,  and  presents 
a  vertical  notch  in  front  for  the  middle  straight  ligament  of  the 
patella.  At  the  sides  are  two  processes,  to  which  the  lateral 
ligaments  are  attached,  the  external  being  the  largest,  and 
presenting  also  an  articular  facet  for  the  head  of  the  fibula. 
Between  this  process  and  the  anterior  tuberosity  is  a  deep  groove, 
for  the  passage  of  the  tendinous  part  of  the  flexor  metatarsi 
muscle. 

The  distal  extremity,  much  smaller  than  the  proximal,  and 
flattened  transversely,  presents  two  smooth,  deep  articular 
grooves,  which  run  obliquely  backwards  and  inwards,  the  internal 
being  the  deepest,  and  the  external  the  widest ;  also  three  pro- 
jections, the  middle  one  forming  a  division  between  the  groves, 
being  articular  and  continuous  with  them,  while  the  others,  which 
form  the  lateral  processes  or  Tnalleoli,  are  roughened  outside  for 
the  reception  of  ligaments.  The  articular  surface  corresponds  to 
the  trochlea  of  the  astragalus  articulating  with  it.  The  internal 
malleolus  is  the  most  prominent,  and  the  external  the  widest, 
being  grooved  for  the  passage  of  the  tendon  of  the  peroneus 
muscle. 


ASTRAGALUS, 


FIBULA. 
(PL.  L  //.) 

This  is  a  long  slender  bone,  little  developed  in  the  horse,  and 
is  an  appendage  to  the  tibia,  being  attached  to  the  outer  side 
of  that  bone,  and  extending  from  its  head  to  its  lower  third,  to 
which  it  is  affixed  by  a  ligement ;  the  space  between  the  two 
bones  is  called  the  tibial  arch. 

The  head,  or  superior  part,  is  nodular,  somewhat  flattened, 
and  roughened  externally  for  the  attachment  of  the  external 
lateral  ligament  of  the  joint  above  ;  internally  it  articulates  with 
the  external  lateral  part  of  the  head  of  the  tibia.  Distally  the 
bone  becomes  slender,  and  tapers  to  a  point,  from  which  a  liga- 
ment is  sometimes  continued  the  whole  length  of  the  tibia.  The 
peroneus  muscle  arises  chiefly  from  the  fibula. 

TARSUS. 

The  tarsus,  or  hock,  corresponding  to  the  ankle-joint  of  a  man, 
is  composed  of  six  irregular,  compact  bones,  placed  between 
the  distal  end  of  the  tibia  and  the  proximal  end  of  the  meta- 
tarsus ;  they  are  arranged  in  two  series  ;  one.  consisting  of  the 
cuboid  and  three  cuneiform  bones,  the  magnum,  medium,  and 
parvum,  corresponds  to  the  lower  row  of  carpal  bones  ;  the 
other,  or  upper  series,  consists  of  the  astragalus  and  calcaneum 
the  first,  forming  with  the  bone  above  the  mobile  portion  of  the 
joint,  may  be  said  to  correspond  to  the  upper  row  of  carpal 
bones,  while  the  latter,  being  the  lever  bone,  corresponds  to  the 
trapezium.  These  bones,  like  those  of  the  carpus,  are  thickly 
covered  on  their  articular  surfaces  by  cartilage,  which  acts  as  a 
protection  against  concussion.' 

ASTRAGALUS. 
(Fig.  22.  2.) 

This,  otherwise  termed  the  os  tali  or  ankle  bone,  is  a  pulley- 
like bone,  placed  immediately  below  the  tibia,  with  which  it 
articulates.  A  very  large  proportion  of  the  surface  of  this  bone 
is  articular. 

The  superior  or  supero-anterior  surface  presents  an  articular 


94 


OSTEOLOGY. 


trochlea  consisting  of  two  oblique  prominences,  separated  by  a- 
deep  groove,  directed  downwards  and  outwards,  which  corres- 
pond to  the  articular  surface  on  the  distal  end  of  the  tibia.  The 
inferior  surface  is  concavo-convex,  and  excepting  a  small  oval 
external  portion,  which  rests  on  part  of  the  cuboid  bone,  and  a 
roughened,  excavated  posterior  portion,  in  which  the  great  inter- 
osseous ligament  is  attached,  the  whole  of  it  articulates  with  th& 
superior  surface  of  the  cuneiforme  magnum.  The  posterior 
surface  is  very  irregular,  and  has  four  facets,  which  articulate 
with  the  calcaneum,  the  intervening  portion  being  excavated 
and  roughened.  The  lateral  surfaces,  the  internal  of  which  pre- 
sents a  tubercle  inferiorly,  are  roughened 
for  the  insertion  of  ligaments.  The  astra- 
galus articulates  with  the  tibia  and  calcan- 
eum, the  cuboid,  and  great  cuneiform  bones. 

CALCANEUM. 

(Fig.  22.  L) 

The  OS  calcis  or  calcaneum,  which  forms 
the  prominent  part,  termed  the  i-)oint  of  the 
hock,  and  corresponds  to  the  heel-bone  of 
man,  is  situated  immediately  behind  the 
astragalus,  and  consists  of  a  body  and  a 
tuberosity.  The  hody  is  the  inferior  por- 
tion, which  is  flattened  laterally,  slightly 
convex  externally,  and  unevenly  concave 
internally,  both  surfaces  being  roughened. 
Anteriorly  it  has  four  articular  facets,  which 
correspond  to  those  on  the  astragalus,  the  interspaces  being 
rough  for  ligamentous  attachment ;  posteriorly  it  is  grooved  and 
smooth,  for  the  passage  of  the  deep  flexor  pedis  tendon  ;  infer- 
iorly it  has  two  facets  to  articulate  with  the  cuboid  bone. 

The  tuberosity  is  oblong,  and  flattened  laterally,  its  external 
surface  being  rough  ;  internally  it  is  smooth,  and  forms  the  tarsal 
arch,  a  groove  covered  with  fibro-cartilage,  in  which  lies  the  above- 
named  flexor  pedis  tendon.  Both  borders  are  roughened,  the 
posterior  one  being  straight,  and  giving  attachment  to  the 
calcaneo-cuboid  ligament,  while  the  anterior  and  shorter  one  is. 
curved.  The  superior  extremity  is  expanded  and  roughened  ; 
posteriorly   it  is   covered   with   fibro-cartilage,    over    which    thft 


Fig.  22. 
Bones  of  left  tarsus  of  a 
Horse,  seen  from  the  front 
and  outside.  1,  Calcaneum  ; 
2,  Astragalus  ;  3,  Cuneiforme 
magnum:  4,  Cuneiforme  med- 
ium :  5,  Cuboid. 


OS   CUNEIFOKME   MAGNUM.  95 

tendon  of  the  flexor  perforatus  muscle  plays  ;  and  anteriorly  is  a 
smaller  portion,  also  covered  with  cartilage,  for  the  gastrocne- 
mius tendon  to  play  over  ;  and,  finally,  a  roughened  depression 
between  the  two  smooth  portions  for  the  insertion  of  the  last 
named  tendon.  The  calcaneum  articulates  with  the  astragalus 
and  cuboid  bones. 

OS  CUBOIDES. 
(Fig.  22.  5.) 

The  cuboid  bone  is  a  small  irregularly-shaped  bone,  which 
occupies  the  outer  part  of  the  hock  between  the  os  calcis  and 
the  large  and  outer  small  metatarsal  bones ;  it  presents  four 
surfaces. 

The  external  svurface  is  convex,  very  rough  and  irregular,  and 
gives  attachment  to  ligaments  ;  the  internal  surface  has  four 
articiilar  facets,  the  two  superior  of  which  articulate  with  the 
cuneiforme  magnum,  and  the  two  inferior  with  the  cuueiforme 
medium ;  between  the  upper  and  lower  facets  a  large  foramen  is 
formed  by  these  three  bones,  giving  passage  to  the  perforating 
pedal  artery.  The  superior  surface  is  smooth,  and  possesses 
two  continuous  articular  facets,  one  large,  to  articulate  with  the 
OS  calcis,  and  the  other  small,  to  articulate  with  the  astragalus  ; 
the  inferior  surface,  also  smooth,  has  two  continuous  articular 
facets,  separated  by  a  ridge,  one  flat,  to  articulate  with  the  large 
metatarsal,  and  the  other  bevelled,  to  articulate  with  the  outer 
small  metatarsal  bone. 

The  cuboid  articulates  with  six  bones — viz.,  the  calcaneum  and 
astragalus  above,  the  cuneiforme  magnum  and  medium  internally, 
and  the  large  and  external  small  metatarsal  bones  below. 


OS  CUNEIFORME  MAGNUM. 
(Fig.  22.  3.) 

The  large  cuneiform,  called  also  the  scaphoid,  and  sometimes 
"the  navicular  bone,  is  the  bone  on  which  the  astragalus  chiefly 
rests ;  it  is  somewhat  flattened  and  thin,  and  presents  two  sur- 
faces and  a  circumferent  border.  The  superior  surface  is  concave 
and  entirely  articulatory,  with  the  exception  of  a  groove  which 
runs  from  its  outer  surface  to  its  middle,  and  gives  attachment 
to  a  ligament ;  this  surface  articulates  with  the  astragalus.   The 


96 


OSTEOLOGY. 


inferior  surface  is  slightly  convex,  and  presents  three  articular 

facets,  two  of  them,  separated  by 
a  rough  excavation,  articulating 
with  the  cuneiforme  medium, 
while  the  third  is  small,  and 
articulates  with  the  cuneiforme 
parvum  behind.  The  anterior 
and  internal  lateral  borders  are 
rough,  for  ligamentous  attach- 
ment; the  external  lateral  border 
has  two  facets,  which  articulate 
with  the  cuboid,  the  intervening 
portion  being  roughened.  The 
posterior  border,  the  smallest,  is 
irregular,  and  gives  attachment 
to  ligaments.  The  large  cunei- 
form bone  articulates  with  the 
astragalus,  the  cuboid,  mediunv 
and  small  cuneiform  bones.' 


OS  CUNEIFORME  MEDIUM. 

(Fig.  22.  4.) 

The  median  cuneiform  bone 
is  somewhat  flattened  and  tri- 
angular in  shape,  and  a  little 
smaller  than  the  magnum,  under- 
neath which  it  is  placed. 

The  superior  surface  is  con- 
cave, and  presents  two  articular 
surfaces  for  the  magnum,  with 
a  roughened  transverse  space 
between.  The  inferior  surface 
is  convex,  and  rests  on,  and 
articulates  with,  the  large  meta- 
tarsal bone.  The  anterior  border 
is  rough,  for  ligaments ;  the 
external  lateral  border  has  two 
facets  for  articulation  with  the 
cuboid,  with  a  roughened  depres- 
lateral   border  has  one   very  small 


Fig.  2a. 
External  view  of  bones  of  left  tarsus,  meta- 
tarsus, and  digit  of  a  Horse.  1,  Distal  end 
of  tibia ;  2,  Calcaneum  ;  3,  Astragalus  ;  4, 
Cuboid  ;  5,  Cuneiforme  magnum  ;  6,  Cunei- 
forme medium ;  7,  Great  metatarsal :  8,  Exter- 
nal small  metatarsal  (splint);  9,  Proximal 
phalanx  (os  suffraginis) ;  10,  Sesamoids;  11, 
Median  phclanx  (os  coronas);  12,  Distal 
phalanx  (os  pedis);  14,  Third  Sesamoid  (os 
naviculare) ;  15,  Basilar  process. 

sion  between :   the  internal 


OS    METATARSI    MAGNUM. 


97 


facet,  which  articulates  with  the  cuneiforme  parvum,  the  remain- 
ing portion  being  excavated  and  roughened.  The  middle 
cuneiform  articulates  with  the  large  and  small  cuneiform,  the 
cuboid,  and  the  large  metatarsal  bones. 


OS    CUNEIFORME    PARVUM. 

The  small  cuneiform  is  a  very  irregular  bone, 
and  the  smallest  in  the  hock,  at  the  postero- 
internal part  of  which  it  is  situated.  It  is 
sometimes  divided  into  two  parts,  and  presents 
four  surfaces  and  two  extremities.  Its  superior 
surface  is  smooth  and  concave,  to  articulate  with 
the  magnum ;  and  its  inferior  surface  has  usually 
two  small  facets,  one  articulating  with  the  inner 
small  metatarsal,  the  other  with  botb  the  inner 
and  large  metatarsal  bones.  The  anterior 
extremity  presents  a  very  small  facet  for  the 
cuneiforme  medium,  the  remainder  of  the  bone 
being  very  irregular,  and  roughened  for  ligaments. 
The  small  cuneiform  articulates  with  the  large 
and  middle  cuneiforms,  and  the  large  and  inner 
small  metatarsal  bones. 


Metatarsus, 
os  metatarsi  magnum. 

^FiG.  24.) 

This  bone  presents  the  same  general  appear- 
ance as  the  large  metacarpal  bone,  from  which  it 
differs  principally  in  being  about  one-sixth  longer, 
flattened  laterally,  and  rounded  and  more  pro- 
minent anteriorly.  It  has  three  articular  facets 
on  its  superior  surface,  a  large  one  in  the  middle  for  the  middle 
cuneiform,  one  on  the  inner  side  for  the  small  cuneiform,  and 
one  on  the  outer  side  for  the  cuboid  bones  ;  this  surface  also 
presents  a  deep,  rough  fossa  of  insertion  in  its  centre.  The  deep 
groove  which  passes  obliquely  backwards  and  downwards,^  on  the 
external  side  of  this  bone,  is  for  the  passage  of  the  great  meta- 
tarsal artery.  The  inferior  extremity  is  larger  and  thicker  than 
the  superior. 


Posterior  view  of 
left  metatarsus  of  a. 
Horse.  1,  Large  me- 
tatarsal bone  ;  2,  In- 
ternal, and  3,  exter- 
nal, small  metatarsal 
bones ;  4,  Partial 
origin  of  suspensory 
and  check-ligaments; 

5,  Nutrient  foramen; 

6,  Articular     ridge 
joining  the  condyles. 


98  COMPARATIVE    OSTEOLOGY. 

OSSA    METATABSI     PARVA. 
(Fig.  24.  2,  3.) 

These  also  present  the  same  general  form  «*«?  ihe  small  meta- 
carpal bones ;  the  external  is  the  longest  and  largest,  and  has  the 
largest  head,  with  two  facets  which  articulate  with  the  cuboid 
bone ;  the  internal  one  has  also  three  articular  facets,  two  for  the 
small,  and  one  for  the  middle  cuneiform  bones.  The  two  lateral 
facets  on  each  head  articulate  with  corresponding  ones  on  the 
large  metatarsal  bone. 

The  remaining  bones  of  the  hind  extremity — viz.,  the  three 
phalanges,  with  their  three  small  accessory  bones,  so  closely 
resemble  the  corresponding  bones  of  the  fore  extremity,  that 
it  seems  at  first  sight  difficult  to  distinguish  the  one  from  the 
other ;  the  chief  differences  being,  that  the  first  phalanx  of  the 
hind  extremity  is  longer,  its  proximal  end  larger,  and  its  distal 
end  smaller,  than  in  the  fore  extremity.  The  second  phalanx  is 
longer,  but  not  so  broad  transversely,  and  the  third  is  more  pointed, 
or  semi-eliptical,  in  front,  and  more  concave  on  its  under  surface, 
air  these  differences  being  more  or  less  marked  in  degree.  The 
three  sesamoid  bones  are  almost  identical 


COMPAKATIVE  OSTEOLOGY. 

In  this  section  of  the  subject  we  shall  endeavour  to  point  out  where  the  skele- 
tons of  the  domesticated  animals,  other  than  the  horse,  differ  from  the  typical 
skeleton  of  the  latter  in  any  important  particular.  The  following  descriptions 
are  therefore  in  all  cases  comparisons,  where  comparison  is  possible,  between 
the  typical  skeleton  and  the  skeleton  in  question. 

RUMINANTIA. 
In  this  class  we  take  the  Ox  as  the  animal  which  represent?  best-  for  oui 
purpose,  the  family  Cavicornia  or  Bovidfe. 

Axial  Skeleton, 
the  skull. 
In  the  cranium  of  the  ox  an  important  feature  is  the  development  of  the 
frontal  bone,  which  extends  from  below  the  eyes  to  the  back  of  the  skull, 
forming  the  entire  forehead  and  crest,  in  the  middle  of  which  is  the  frontal 
tuberosity,  which  is  very  large  in  hornless  animals.  Springing  from  the  sides 
of  the  crest  are  two  processes,  varying  in  size  and  curvature,  but  corresponding 


RUMINANT   SKELETON. 


99 


SKELETON  OF   THE  OX  (Ruminaniia). 
AxiAx  Seeletok. 


Cranial  Bone«.— Occipital,  1;  b,  Parietal,  2;  a.  Frontal,  2;  c,  Temporal,  2;  Sphenoid,  1; 
JSthmoid,  1 ;  Auditory  ossiclss,  8. 

Facial  Bones.— h,  Nasal,  2  ;  e.  Lachrymal,  2 ;  d,  Malar,  2  ;  /,  Maxilla,  2  ;  g,  Premaxilla,  2 ; 
i.  Inferior  maxilla,,  2;  Palatine,  2;  Pterygoid,  2;  Vomer,  1;  Turbinals,  4  ;  Hyoid  (segments),  7. 
Teeth  :— Incisors,  6  ;  Canines,  2  ;  Molars,  24. 

The  Trunk.— k.  Cervical  Vertebrae,  7;  I,  Dorsal  vertebrae,  13;  m,  Lumbar  verteb-»,  6;  n,  Sacrum 
■<five  segments),  1 ;  o.  Coccygeal  vertebrae  (variable),  20 ;  p  p.  Ribs,  26 ;  *  Sternum  (seven  steme- 
brae),  1;  St  Costal  cartilages. 

Appendicular  Skeleton, 

PECTOEAl  LIMB. 

t,  Scapula,  2;  u.  Humerus,  2 ;  v,  Radius,  2 ;  w,  Ulna,  2.  Carpus:— x,  Trapezium,  2;  y,  Cunei- 
form, 2;  e,  Limar,  2;  a'.  Scaphoid,  2;  b',  Unciform,  2;  &,  Magnum,  2.  Metacarpus  :—d',  Large 
bone,  2 ;  e'.  Small  bone,  4  ;  /,  Large  sesamoids,  8.  Digit :— g',  Proximal  phalanges,  4 ;  h',  Median 
phalanges,  4 ;  i'.  Distal  phaUnges,  4 :  k^,  Small  sesamoids  (naviculars),  4. 


pelvic  limb. 

Pehiis.—Os  Innominatum  :—q.  Ilium,  2  ;  s,  Ischium,  2  ;  r.  Pubis,  2. 

The  Limb.— I',  Femur,  2 ;  m'.  Patella,  2 ;  «',  Tibia,  2.  Tarsus :— (f ,  Maleolar,  2;  i)',  Calcaneum,  2; 
Q*,  Astragalus,  2 ;  /,  Cubo-cuneiform,  2 ;  s*,  Cuneiforme  medium,  2 :  t*,  Cuneiforme  parvum,  2. 
Metatsraus :— Large  bone,  2 ;  u',  Small  bone,  2.  Large  sesamoids,  8.  Digit :— Proximal  phalanges. 
4 ;  Median  phalanges,  4 ;  Distal  phalanges,  4 ;  Small  sesamoids,  4. 

VisoEBAi,  Skeleton. 
Bones  of  the  heart,  2. 

The  separate  bones  of  the  Bnminant  Skeleton,  as  here  considered,  are  261. 


100 


COMEARATLVE    OSTEOLOGY. 


to  the  shape  of  the  horns,  which,  they  support.  These  are  the  flints  or  horti 
cores,  which  are  porous  in  their  structure,  especially  at  the  roots  ;  they  are  very 
rough,  covered  by  thick  periosteum,  and  contain  sinuses,  large  canals,  ancF 
foramina,  through  which  pass  arteries  and  veins,  and  wiiich  are  continuou? 
with  the  largely-developed  frontal  sinuses  ;  the  latter  extend  from  the  orliit 
to  the  extremities  of  the  cores,  and  nearly  as  far  backwards  and  downward? 
as  the  foramen  magnuui.  The  superior  surface  of  the  frontal  bone  is  flat  and 
broad,  especially  in  the  male.  The  supraorbital  foramina  are  double,  place  J 
very  far  backwards,  and  continued  by  a  groove  which  extends  backwards  and 
forwards^  j^The  frontal  arch  articulates  with  the  malar  portion,  of  the  zygoma/' 


FiC.  20, 

SKTLL  OF  AN  Ux. —Superior  Aspect. 

a.  Frontal  crest;  b,   Lateral  crest;  c  c  c,  Horn  ccfre, 

d,    N'asal    peak ;    e.    Supraorbital    foraoiina:     .Bones  T— 

li  Frontal  ;  2>  Lachrymal ;  3    Malar ;    4.  Superior  mazil> 

lary  ;  5.-  N'asal;  6.  Premaxilla,  with  Incisive-openiugs. 

The  parietal  bone  is  transversely  elongated,  and  recurved  at  its  extremftie^ 
It  V8  placed  below  the  frontal  crest,  extending  under  and  siipportipg  the  coresj 
and  entering  the  temporal  fossa  to  articulate  with  the  sphenoid  and  temporal 
bones.  Beneath  the  crest  posteriorly  it  forms  with  its  fellow  the  inter- parietal 
euiure. 

The  Wormian  bone  exists,  fused  with  the  occipital  and  parietals.  It  is 
described  as  "  wanting,"  by  some  authorities. 

The  occipital  bone  is  not  visible  when  the  skull  is  viewed  superiorly,  being 
concealed  by  the  prominent  frontal  crest.  It  is  much  wider  from  side  to  side, 
but  smaller  than  in  the  horse.  It  has  neither  crest  nor  tuberosity,  the  condyles 
being  less  prominent,  but  wider  ;  the  styloid  processes  are  shorter,  but  broader,, 
and  curved  inwards.  The  basilar  process  is  short  and  thick,  with  a  lai^e 
basilar  groove,  and  two  rough  prominences  for  muscular  attachmeat  anteriorly  ! 
J'he  condyloid  foram{na^are_double,  sometimes  triple.^ 


RUMINANTIA THE    SKULL.  101' 

The  squamosal  and  petrosal  bones  are  united  into  a  single  temporal  -  bone. 
The  teinporo-maxillary  articulation,  zygomatic  process,  temporal  conduit^  the 
auditory  bulla,  and  styloid  process,  are  large.  The  zygomatic  process  does 
not  articulate  with  the  frontal  bone.  The  foramen  lacerum  basis  cranii  is 
-considerably  occluded  by  the  prominence  of  the  auditory  bulla.  The  external 
£\iiditory  meatus  is  small,  and  directed  slightly  downvvard-s. ,  Immediately 
•behind  the  sella  turcica  is  a.  slight  and  rough  eminence,  very'  prominent  in. 
some  classes,  the  posterior  clinoid  process.  ' 

The  sphenoid  has  large  and  thin  pterygoid  processes,  a  deep  sella  turcica,  anct 
a  prominent  olivary  process.  The  pterygoid  foramen  is  absent ;  the  foramen 
•lacerum  basis  cranii  small,  its  place  being  largely  occupied  by  the  auditory 
bulla,  but  there  is  a  large  foramen  ovale,  for  the  passage  of  the  inferior  maxil- 
lary nerve  and  the  spheno-spinal  artery.  The  foramen  lacerum  orbitale,. 
foramen  patheticum,  and  foramen  rotundum  are  represented  by  an  anterior 
common  foramen. 

The  ethmoid  and  its  cells  are  well  developed.  It  has  a  large  volute,  pro- 
longed forwards,  forming  a  kind  of  third  turbinal  bone,  called  the  olfactory 
cave  (antre  olfactif). 

The  nasal  bones  are  shorter,  narrower,  and  not  so  firmly  articulated  as  those 
of  the  horse.  The  posterior  extremity  is  sunk  in  a  groove  in  the  anterior 
border  of  the  frontal  bone  ;  tlie  anterior  extremity  presents  two  points  with  a 
notch  between  them,  the  central  pair  joining  to  form  one  ;  therefore  the  nasal 
peak  is  trifid  ;  in  the  smaller  ruminants  it  is  usually  double,  , 

The  superior  maxilla  is  shorter  but-broader,  the  maxillary  spine  being  repre- 
sented by  a  rough  protuberance,  not  continuous  with  the  zygoma.  The  infra- 
orbital foramen  is  opposite  the  first  molar  tooth.  The  maxillary  sinus  is  large,, 
and  is  prolonged  between  the  two  plates  pf  the  palatine  bone.  There  is  nc 
alveolus  anteriorly  for  a  canine  tooth.  This  bone  does  not  assist  in  forming 
the  palatine  foramen. 

The  premaxilla  is  broad  ;  its  inferior  surface  is  flat  and  destitute  of  alveolar 
cavities.  There  is  no  incisive  foramen,  but  very  large  incisive  openings.  The 
premaxillse  are  rarely  united  by  suture. 

The  lachrymal  bone  is  large,  forming  at  the  bottom  of  the  orbit  a  large- 
lachrymal  protuberance  continuous  with  the  maxillary  sinus.  The  wall  of 
this  protuberance  is  thin  and  fragile.     The  lachrymal  tubercle  is  absent. 

The  malar  bone  is  well  developed.  Posteriorly  it  is  bifid  ;  the  superior 
branch  meets  the  orbital  process  of  the  frontal  bone,  and  the  posterior  joins-, 
the  zygomatic  process  of  the  temporal  bone,  behind  the  orbital  fossa. 

The  palatine  bones  are  large,  the  part  entering  into  the  formation  of  the. 
bony  palate  being  broad.  The  palatine  crest  is  thin  and  elevated,  being  formed 
"by  the  union  of  the  posterior  borders  of  the  palatine,  pterygoid,  and  pterygoid , 
process  of  the  sphenoid  bones.  .  The  posterior  nares  are  very  narrow,  and' 
situated  behind,  not  between,  the  superior  maxillaj. 

The  pterygoid  bones  are  large,  and  usually  close  an  opening  which  is  left 
between  the  sphenoid  and  palatine  bones. 

The  superior  turbinal  is  small,  while  the  inferior  one  is  largely  developed. 

The  vomer  is  very  large,  resting  on  the  anterior  half  of  the  maxillary  suture. 

The  inferior  maxilla  is  longer  but  less  massive  than  in  the  horse  ;  the  neck 
3a  more  constricted,  and  the  symphysis  seldom  becomes  completely  ossified^ 


103  COMPARATIVE   OSTEOLOGY 

There  are  eight  small  alveoli  in  front  for  the  incisors  and  canines,  the  latter 
being  close  up  to  the  former  ;  the  condyles  are  small  and  convex  in  their 
short,  but  slightly  concave  in  their  long  diameter,  permitting  considerable 
lateral  motion  to  the  joint.  The  coronoid  processes  are  long,  and  the  sigmoid 
notches  very  deep. 

The  OS  hyoides  has  a  cornu  and  two  cornicula  on  each  side — the  former 
(stylchyals)  are  suspended  from  the  temporal  bone.  The  spur  process  is  small 
and  blunt. 

VERTEBRA. 

The  true  vertebral  column  is  made  up  of  26  segments— 7  cervical,  13  dorsal, 
and  6  lumbar.  The  bodies  of  the  cervical  vertebrae  are  shorter  than  those  of 
the  horse  ;  the  transverse  processes  consist  of  a  superior,  small,  and  an 
inferior,  large  portion,  pierced  by  the  vertebral  foramina  ;  the  neural  spines 
are  large,  and  increase  from  before  backwards  ;  the  inferior  spines  unite  the 
anterior  and  posterior  articular  ends.  The  atlas,  smaller  than  that  of  the 
horse,  has  its  alse  more  horizontal  and  slightly  turned  up  at  the  external 
borders.  The  spinal  foramen  is  large,  and  the  posterior  lateral  one  absent.  The 
condyloid  articulations  are  wide,  that  for  the  dentata  being  small  and  flat. 
The  dentata  is  short,  the  odontoid  process  being  broad,  bounded  below  by  a 
prominent  articular  ridge,  which  is  not  excavated  in  the  inferior  median  line  ; 
the  neural  spine  does  not  bifurcate  nor  become  continuous  with  the  posterior 
articular  processes.  The  pedicles  on  either  side  are  perforated  by  a  circular 
foramen. 

The  sixth  cervical  vertebra  has  long  superior  spinous  and  transverse  pro- 
cesses, but  no  inferior  spine.  The  seventh  neural  spine  is  the  longest,  and 
points  backwards  and  upwards;  the  transverse  processes  are  single,  and  ter- 
minate in  rough  tuberosities  ;  there  is  no  inferior  sj)ine,  and  seldom  a  vertebral 
foramen. 

The  centra  of  the  dorsal  vertebrae  are  longer  than  in  the  horse,  but  have 
the  same  general  form  ;  the  pedicles  are  almost  always  pierced  by  foramina  in 
place  of  the  posterior  notches.  The  transverse  processes  are  large,  decreasing 
in  size,  and  assuming  an  arched  form  from  before  backwards  ;  all  but  the 
last,  or  last  two,  present  distinct  articular  surfaces  for  the  costal  tubercles. 
The  neural  spines  are  broad,  long,  and  smooth  :  the  five  or  six  anterior  ones 
incline  backwards,  then  upwards,  the  remainder  simply  backwards  ;  the 
fourth  is  usually  the  longest,  but  the  first  four  or  five  vary  little  in  length. 
The  rest  gradually  become  shorter  backwards  to  the  last.  This  gives  the 
back  when  viewed  laterally  a  very  different  form  from  that  of  the  horse.  The 
lumbar  vertebra?  are  longer  and  thicker  than  in  the  horse,  their  bodies  being 
more  convex  on  the  lateral  and  inferior  surfaces  ;  their  transverse  processes 
are  long,  the  fourth  being  the  longest,  and  they  are  almost  at  right  angles  to 
the  body,  concave  anteriorly,  convex  posteriorly,  the  first  four  being  inclined 
backwards;  they  never  articulate  with  each  other,  nor  does  the  last  with  the 
sacrum.  The  articular  processes  are  small,  the  posterior  being  overlapped  by 
the  anterior  ones. 

The  sacrum  is  large  and  more  arched,  and  the  superior  surface  more  convex 
than  in  the  horse  ;  the  spinous  processes  are  united  by  more  complete  ossifi- 
cation. The  superior  groove  is  narrow  and  uneven,  and  the  superior  forauuna 
not  so  regular  ;  the  under  surface  is  more  concave,  the  promontory  being 


RUMINANTIA PECTORAL    LIMB  103 

better  marked,  and  the  inTerior  foramina  larger.  The  sacral  cornua  are  large, 
aud  expanded  tor  ligamentous  attachment;  the  spinal  canal  is  oval,  and  the 
convex  articular  portion  of  the  body  large,  the  articular  processes  being  widely 
separated  by  a  triangular  opening  leading  into  the  canal.  The  transverse 
processes  are  short,  thick,  and  non-articular  anteriorly  ;  their  external  extremi- 
ties are  bounded  by  a  vertical  border,  the  inferior  angle  of  which  is  directed 
downward?,  giving  a  deeper  surface  for  articulation  with  the  ilium. 

The  coccygeal  bones,  from  15  to  20  in  number,  are  strong  and  tuberous. 
Articular  processes  exist  in  the  anterior  ones. 

THORAX. 

Very  generally  the  ruminants  have  13  pairs  of  ribs,  of  which  8  are  cnio 
and  5  false.  They  are  straight,  broad,  long,  and  more  uniform  than  tho^.a  of 
the  horse  ;  the  superior  extremity  is  large  and  smooth,  the  necks  of  the 
anterior  ones  short  and  thick,  and  the  tubercles  large  ;  the  necks  oi  the 
posterior  ones  are  long  and  thin,  and  smaller  than  in  the  horse.  The  angles 
are  not  well  marked  ;  the  distal  extremities  are  expanded  to  articulate  with 
their  cartilages  by  means  of  true  joints. 

The  sternum  is  large  and  flattened,  consisting  of  seven  pieces,  which,  the 
anterior  one  excepted,  unite  by  ossification  ;  and  between  the  first  segment  or 
manubrium  apd  the  second  there  is,  in  the  larger  ruminant,  a  true  joint.  The^ 
superior  surface  is  concave,  forming  the  floor  of  the  chest,  the  inferior  convex^, 
but  slightly  concave  from  side  to  side.  The  borders  present  between  each  two 
segments  articular  depressions  for  the  costal  cartilages.  The  cariniform 
cartilage  is  small  and  conical,  the  cnsi form  large  an.d  circulai*. 

PECTORAL    LIMB. 

The  scapula  is  large  and  very  triangular.  The  spine  does  not,  as  ;n  the 
horse,  terminate  gradually  in  the  neck,  but  by  an  abrupt  angle,  prolonged  to 
a.  point,  the  acromion  process.  The  neck  is  more  distinct,-  and  the  coracoid 
process  and  glenoid  cavity  are  both  small,  and  placed  close  together.  In  the 
humerus  (Fig.  25.  u),  the  bicipital  groove  is  single  ;  the  external  trochanter 
is  very  large,  with  its  summit  curved  over  the  bicipital  groove.  The  head  is 
large,  the  tuberosities  small,  and  the  shaft  less  twisted,  than  in  the  horse.  The 
1-adius  is  short ;  the  ulna,  longer  and  larger  than  in  the  horse,  extends  to  th2 
tlistal  end  of  the  radius,  and  articulates  with  the  cuneiform  bone.  Tliere  are 
two  radio-ulnar  arches,  connected  by  a  deep  fissure.  It  is  important  to  note 
here  the  fact  that  the  development  of  the  ulna,  and  to  some  extent  its  freedom, 
are  directly  proportional  to  the  number  of  digits  possessed  by  the  animal. 

The  carpus  consists  of  6  bones,  4  above  and  2  .below.  The  upper  are  the 
scaphoid  and  lunar,  which  articulate  with  the  radius  ;  the  cuneiform,  articulat- 
ing with  the  radius  and  ulna  ;  and  the  trapezium,  which  is  small,  tuberOits  in 
fehape,  and  does  not  articulate  with  the  radius.  The  lower  are  the  os  magnuM 
and  unciform,  which  articulate  with  the  large  metacarpal  bone,  the  trapezoid 
and  pisiform  bones  being  wanting ;  the  former,  perhaps,  is  part  of  the  os 
magnum. 

The  large  metacarpal  bone  presents  a  vertical  groove  down  irs  aiitgr'tr 
middle,  which  marks  the  original  division  of  the  bone  into  two.  The  inferior 
extremity  is  divided  by  a  deep  fissure  into  two  articulations,  each  resembling 


104  COMPARATIVE    OSTEOLOGY.'. 

the  single  one  of  the  horse,  the  external  one  being  always  the  smaller  ;  a  rudi- 
cpentary  metacarpal  is  placed  poslero-externally.  The  phalanges  and  sesamoids 
V't  either  limb  are  double,  one  complete  set  forming  each  digit  ;  they  are  small 
-Old  narroW)  the  coffin  bone  resembling  half  of  that  of  the  horse,  niesially 
divided.  Posterior  to  the  fetlock  joint  are  two  rudimentary  digits,  each  con. 
taining  two  undeveloped, phalanges,  the  median  and  the  distal. 


The  OS  innominatum  is  larger,  but  presents  the  same  general  appearance  as 
in  the  horse.  The  ilium  is  thick,  and  possesses  a  prominent  line  running  from 
the  anterior  spine  to  the  superior  ischiatic  ridge.  The  internal  surface  is  very 
convex,  the  ridge  between  the  part  resting  on  and  that  without  the  sacrum 
being  well  marked.  The  ilio-pectineal  eminence  is  prominent,  and  the  crest 
and  spines  very  strong.  The  ischium  equals  the  ilium  in  size  ;  the  anterior 
extremity  has  a  thick  projecting  e.vternal  portion,  which  forms  part  of  the 
cotyloid  cavity,  and  is  surmounted  by  the  large  superior  ischiatic  spine,  whence 
a  slight  ridge  is  continued  backwardb  over  the  thick  concave  body  to  the  tuber- 
osity. The  inferior  ischiatic  spine  is  conical,  pointing  outwards  and  down- 
-wards.  The  ischial  symphysis  presents  inferiorly  a  ridge  and  tubercle,  absent 
in  the  horse.  The  pubis  is  large  and  concave,  and  the  symphysis  is  never 
completely  ossified.  The  acetabulum  is  deep,  and  the  cotyloid  notch  is  nairow 
and  deep,  being  near  the  large  foramen  ovale.  The  inlet  of  the  pelvic 
<;avity  is  oval;  its  sacro-pubic  diameter  is  greater  than  the  transverse  one, 
•-•hile  the  sacro-ischiatic  diameter  of  the  outlet  is  less  than  the  transverse. 

PELVIC   LIMB. 

The  femur  (Fig.  25.  /')  is  distinguished  from  that  of  the  horse  by  the 
trochanter  minor  being  wanting.  The  trochanter  internus  is  a  round  tubercle 
near  the  posterior  surface  ;  the  head  is  small,  but  prominent,  the  trochanteric 
fossa  deep,  but  small  ;  the  trochanter  major  has  only  one  eminence,  not  very 
prominent,  and  is  united  to  the  internal  trochanter  by  a  ridge.  The  condyles 
and  trochlea  are  somewhat  small,  and  the  supracondyloid  fossa  is  shallow.. 
"The  patella  is  narrow,  and  somewhat  conical  in  shape. 

The  tibia  (Fig.  25.  h')  has  no  vertical  fossa  on  the  anterior  tuberosity,  and  no 
articular  facet  for  the  fibula  ;  the  distal  extremity  has  its  external  malleolus 
•detached,  forming  a  small  bone  called  the  malleolar  bone,  which  articulates 
■with  the  tibia,  calcaneura,  and  astragalus,  and  represents  the  distal  end  of  the 
fibula,  the  remainder  of  which  bone,  small  when  present,  is  usually  replaced 
"by  a  long  ligament  stretching  the  whole  length  of  the  tibia. 

The  tarsiis  consists  of  5  bones.  The  astragalus  is  deep,  but  narrow,  having 
A  pulley-shaped  surface  inferiorly  as  well  as  superiorly.  The  calcaneum  is 
lc?.«g  and  square  ;  the  cuneiforme  magnum  and  cuboid  are  united,  forming  the 
Cuba- cuneiform  bone  ;  the  cuneiforme  medium  is  like  that  of  the  horse,  while 
the  parvum  is  very  small. 

The  large  metatarsal  bone  has  its  inferior  extremity  divided  into  two  equal 
parts  by  a  deep  fissure,  with  a  groove  superiorly.  The  small  metatarsal  bones, 
■«vhen  present,  are  rudimentary  and  single.  The  digits  correspond  to  those  of 
the  pectoral  limb. 


OMNIVORA — THE    SKULL 


10.5 


VrscERAL  Skeleton. 

In  the  adult  Euminant,  two  bones  are 
<ommonly  found  in  the  heart,  and  may  be 
termed  the  cardiac  bones  (ossa  cordis).  They 
are  found  related  with  the  auriculo-ventric- 
nlar  rings.  Jn  shape  they  present  three 
angles,  three  borders,  and  two  surfaces.  The 
left  bone  is  considerably  smaller  than  the 
right. 


OMNIVORA. 

The  Omnivora  are  represented  in  Veterin- 
ary Anatomy  only  by  the  Hog. 


Fig.  27., 

Right  cardiac  bone  of  au  Ox— natural 
size,  a,  Anterior  angle ;  &  b,  Posterior 
angles ;  c,  Superior  border ;  d.  Anterior 
border  ;  e,  Posterior  border  ;  /.  Right 
surface 


Axial  Skeleton. 


THE   SKULL 


Skull  of  a  Boar^Idteral  aspect.. 


In  the  skull  of  this  animal  the  following  points  are  noteworthy.  The  siqyra' 
'occipital  bone  forms  a  very  prominent  crest ;  the  occipital  condyles  and  the 
foramen  magnum  are  small  ;  the  styloid  processes  very  long,  inclining  back- 
Iwards.  The  parietal  bones  are  early  anchylosed,  the  superior  surface  being 
'contracted  in  the  middle,  with  a  sharp  ridge  on  each  side,  limiting  the  temporal 
ifossa.  The  orbital  process  of  the  frontal  bone  is  short,  the  frontal  arch  being 
'completed  by  a  ligament;  in  the  centre  of  _ 

jthe  bone,  about  a  third  from  its  anterior 
[border,  is  the  supraorbital  foramen,  and  from 
it  a  groove  passes  forwards  and  oulwaids. 
■The  frontal  bone  articulates  with  the  superior 
liuaxilla.  The  temporal  is  a  smgle  bone  on 
rcach  side  ;  the  ])etrous  portion  is  small,  and 
the  zygomatic  process  large,  bearing  a  promi- 
nent spine.  A  ridge  connects  the  CNternnl 
auditory  meatus,  placed  very  high  np,  with 

;the  mastoid  protuberance,  which  is  very  large,  the  styloid  process  being  short.' 
jThe  maxillary  articulation  is  not  supported  behind  by  a  well-marked  proce.ss,' 
and  is  smallest  transversely..  The  spkenoid  is  short,  with  large,  flat  pterygoid 
processes;  the  wings  do  not  project,  bnt  are  nearly  perpendicular;  the  sella 
turcifca  is  deep,  and  the  olivary  and  clinoid  processes  large. 

The  nasal  bones  are  long,  straight,  and  strong,  firnily  connected  with  the 
frontal  and  superior  maxillary,  but  do  not  articulate  with  the  lachrymal  bones; 
the  nasal  peak  projects  nearly  to  the  level  of  the  incisors.  The  lachrymals  are 
small,  with  lachrymal  fossoe  on  the  supero-cxtemal  part  of  the  bone  instead  of 
in  the  orbit,  as  in  the  horse  and  ox ;  they  are  pierced  by  two  conduit*,  which 
afterwards  form  one.  The  malar  bone  is  very  strong,  and  the  ?yg'jinatic 
process  large,  and  terminating  in  two  branches,  between  which  ,"ssis  the 
zygomatic  process  of  the  temporal  bone;  the  anterior  branch  is  short,  ojid  not 
united  to  the  orbital  arch  of  the  frontal  bone.  The  supenor  moxilla  is  propor-' 
tionally  lather  short  and  narrow,  and  its  surface  concave,  for  the  reception  of 
Jarge  facial  muscles  ;  it  presents  a  large  lateral  protuberance  anteriorly,  whencOj 


106 


COMPARATIVE    OSTEOLOGY, 


SKELETON  OF  THE  HOG  (Omnivora). 
Aytat.  Skeleton. 

XKE   SKTJXL. 

b,  Parietal,  2  ;  d.  Frontal,  2  ;  c,  Temporal,  2  ;  Sphenoid,  1  : 


i,  MaxUla,  2  ;  k,  Pre- 
Tnrbinals,  4  ;  Hyoid 


Cranial  Boms. — a.  Occipital,  1 
Ethmoid,  1 ;  Auditory  ossicles.  8. 

Facial  Bones.— g,  Nasal,  2 ;  ft,  Os  rostri.  1  ;  /,  Lachrymal,  2  ;   e,  Malar,  2 
maxiUa,  2;   I,  Inferior  maxilla.  1;   Palatine.  2;   Pterygoid,  2;   Vomer,! 
series,  j.       Teeth  : — Incisors.  12  ;  Cahines.  4  ;  Molars,  28. 

The  Trunk.— m,  Cervicle  vertebrse,  7 ;  n,  Dorsal  vertebrae.  14  ;  o,  Lumbar  vertebrae,  7  ;  p,  Sacrum, 
(four  segments),  1 ;  5,  Coccygeal  vertebrae  (variable),  IS  ;  r  r,  Kibs,  28  ;  *  Stem>ia>  (seven  sterue- 
brae),  1  ;  ffl  Costal  cartilages. 

Appendicuxar  Skeleton. 

pectoeax  limb. 

V,  Scapula,  2  :  w,  Humerus,  2 ;  x,  Radius.  2  ;  y,  Ulna,  2.  Carpus  :—z,  Trapezium.  2  ;  a',  Cunei- 
form, 2  ;  6',  Lunar,  2  ,  &,  Scaphoid,  2  ;  d'.  Unciform,  2  ;  e',  Magnum,  2 ;  /',  Trapezoid,  2  ;  y",  Pisi- 
form, 2.  Metacarpus  :—7i'.  Bones,  8;  Large  sesamoids.  16.  Digit  :-i'.  Proximal  phalanges.  8? 
k'.  Median  phalanges,  8 ;  I',  Distal  phalanges.  8  :  I",  Small  sesamoids,  8. 

PELVIC    LIMB. 

Pelvis.— Os  Innominatum  :— s.  Ilium,  2  ;  t,  Pubis,  2  ;  u,  Ischium.  2. 

The  Limb.—m',  Femur,  2  ;  n' ,  Patella.  2  ;  0',  Tibia,  2  ;  p'.  Fibula.  2.  Tarsus  :-  g',  Calcaneum.  3  . 
r',  Astragalus,  2  ;  s'.  Cuboid,  2  ;  f ,  Cuneiforme  magnum,  2  ;  u',  Ecto-cuneiforme.  2  ;  1/  w,  Meso- 
and  Endo-cuneiformes,  4.  Metatarsus  :— Large  bones,  8  ;  x'.  Small  bones,  2  ;  j/'.  Large  Sesamoids. 
16.   Digit :— Proximal  phalanges,  8 ;  Median  phalanges.  8  ;  Distal  phalanges.  8  ;  Small  sesamoids.  S. 

Visceral  Skeleton. 

None. 

The  separate  bones  of  the  Skeleton  of  the  Hog,  as  here  considered,  are  324. 


OMNIVOKA VERTEBRA.  107 

springs  the  tusk ;  the  alveoli  for  the  molar  teeth,  usually  seven  in  number, 
gradually  increase'  in  size,  from  the  anterior  one,  which  is  very  small, 
to  the  last,  largely  developed  and  strong.  The  maxillary  sinus  is  small, 
projecting  into  the  malar  bone  ;  the  palatine  foramen  opens  on  the 
palatine  plate  of  the  maxilla,  before  the  palatine  bone.  The  premaxilla. 
is  large  and  strong ;  it  is  not  joined  at  the  symphysis,  and  consequently 
forms  no  foramen  incisivun^ ;  its  external  process  is  very  long,  and  articu- 
lates largely  with  the  nasal  bone  ;  there  are  three  alvfeoli  on  each  side  for 
the  incisor  teeth.  Part  of  the  septum  of  the  nose  becomes  ossified,  forming 
the  prenasal  or  snout  bone  (os  rostri).    The  anterior  nares  are  small  and  round. 

The  imlatine  bones  form  a  large  portion  of  the  bony  palate  ;  their  orbital 
portion  is  very  small.  The  palatine  ridge  is  replaced  by  a  tuberosity,  with 
which  the  pterygoicT  process"  of  the  sphenoid  bone  articulates  externally,  and 
the  pterygoid  bone  internally,  and  the  union  of  these  tliree  parts  results  in  a 
large  trifid  tubercle. 

The  turhinals  are  longer  and  less  fragile  than  in  the  horse. 

The  inferior  maxilla  is  very  strong,  having  no  well-defined  neckj  "and  small 
interdental  spaces  ;  the  coronoid  process  is  short,  but  strong,  and  the  condyles, 
somewhat  nodular,  are  compressed  laterally.  The  dental  canal  terminates 
anteriorly  by  numerous  small  mental  foramina  ;  and  the  alveoli  for  the  molars 
are  seven  in  number.  Posteriorly  this  bone  bears  a  certain  resemblance  to  the 
corresponding  human  bone.  The  symphysis  becomes'  early  ossified  in  this 
animal. 

The  OS  hyoides  has  a  large  body,  but  no  appendix.  The  cornicula  are  short, 
while  the  cornua  are  thin,  twisted  somewhat  like  the  letter  S,  and  united 
to  the  temporal  bones  by  elastic  ligaments. 


FlC.  30. 

longitudinal  Section  of  a  Hog's  Skull.     1,  Os  rostri;  2,  Maxillary  Tur. 

binal;  3,  Frontal  Turbinal ;  4,  Large  Ethmoidal  .volute;  5,  Occipital  Styloid 

process;  6  C  6",  Frontal  Simis;  7,  ^asal  chamber:  S  8',  Cranial  cavity; 

9,  Auditory  bulla, 

VERTEBUiE, 

'The  true  vertebral  column  consists  of  28  vertebrae. — 7  cervical,  14  dorsal,  and 
I  7  lumbar.  The  cervical  vcrlcbrce  are  very  short,  convex  below,  and  without 
inferior  spines  ;  the  transverse  processes  are  bifid,  and,  excepting  the  last,  the 
posterior  ones  are  large  and  overlapping.  The  articular  processes  are  strong, 
the  anterior  being  pierced  by  a  foramen  entering  the  spinal,  canal.  The 
transverse  processes  are  small  and  generally  pierced  by  vertebral  foramina. 
I'The  atlas  is  strong,  rough,  and  irregular,  presenting  a  large  tuberosity  on  its 
superior  surface  ;  the  wings  are  strong,  particularly  at  their  posterior  borders  ; 


108  COMPARATIVE    OSTEOLOGY. 

the  posterior  foramen  is  inconstant,  usually  openhig  on  the  posterior  edge. 
Tl)c  axis  is  broad  anteriorly,  with  a  small  otlontoid  process,  and  extended 
articular  surfaces;  small  transverse  processes  are  pierced  by  large  vertebral 
foramina  ;  the  neural  spine  is  tall  and  thin.  Tire  five  posterior  segments  have 
large  neural  spines,  the  promincns  especially  so. 

There  are  usually  14  dorsal  vertebra;,  with  short  centra,  increasing  in  length 
from  before  backwards.  The  neural  spines  are  broad,  decreasing  gradually 
from  the  first  backwards  ;  the  first  is  nearly  upright,  the  rest  slope  backwards, 
excepting  the  last  two  or  three,  whicli  are  slightly  inclined  forwards.  Two^ 
foramina  enter  the  neural  canal  on  each  side  from  the  base  of  the  transverse 
process.  The  lumbar  vertebrre  number  6,  sometimes  7  ;  their  centra  are 
longer  than  in  any  other  region,  resembling  those  of  the  ruminant.  The 
neural  spines  are  strong-pointed,  and  bifid  at  the  posterior  borders,  the 
diverging  laminis  being  continuous  with  the  posterior  oblique  processes  ;  the 
transverse  processes  are  long,  nearly  horizontal,  and  without  articular  surfaces  ; 
the  base  of  each  is  pierced  by  a  small  foramen  leading  into  the  neural  canal 
The  sucmm  is  usually  made  up  of  4  segments  ;  the  neural  spines  are  very 
rudimentary,  in  fact  the  laminse  scarcely  coalesce,  leaving  the  neural  canal 
partly  open  ;  the  articular  processes  are  large  and  overlap  those  of  the  last 
lumbar  vertebra.  The  coccygeal  bones  vary  in  number,  being  usually  from  18 
to  23,  and  the  anterior  ones  have  articular  processes. 

Generally  there  are  14  pairs  of  ribs— 7  true  and  7  false.  They  are  thin  and 
■fiat,  the  last  three  having  their  tubercles  and  the  posterior  part  of  their  heads 
united.  The  second,  third,  fourth,  and  filth  have  true  articulations  distallv. 
The  sLemum  is  very  long,  and  consists  usually  of  7  segments,  the  manubrium 
•femaining  separate  as  in  the  ox.  The  cariniform  cartilage  fortus  a  long 
eminence  terminating  in  a  blunt  point. 

Appendicular  Skeleton, 
pectoral  limb. 
The  scapula  is  large,  without  an  acromion  process  ;  it  has  a  prominent 
spine,  bearing  in  its  centre  a  large  tuberele,  which  inclines  backwards  over 
the  postea-spinatus  fossa.  The  Mimerus  is  short,  and  compressed  laterally,  the 
head  inclining  backwards  ;  the  bicipital  groove  is  single,  and  the  external 
trochanter  is  very  large,  with  i-ts  summit  curved  over  the  bicipital  groove,  as 
in  -the  ox  ;  the  external  tuberosity  is  small,  the  internal  one  being  replaced 
bv  muscular  imprints.  The  radius  is  small,  and  much  curved  ;  while  the  ulna 
is  a  true  long  bone,  having  a  xiiedullary  canal,  and  extending  to  the  carpus, 
with  which  it  articulates.  The  radius  and  ulna  are  united  by  ligaments, 
which  rarely  become  ossified.  The  ulna  is  flattened  from  side  to  side,  and  lies 
on  the  posterior  face  of  the  radius,  in  close  connection,  except  that  there  exists 
a  radio-ulnar  arch.  The  olecranon  is  prominent.  The  carpus  consists  of  8 
bories,  4  in  the  upper  and  4  in  the  lower  row.  The  bones  of  the  up^jer  row- 
are  similar  to  those  of  the  horse,  the  cuneiform  articulating  above  wiih  the 
ulrsa  and  a  small  portion  of  the  radius,  the  lunar  and  scaphoid  bones  with  the 
radius,  but  the  trapezium  with  neither  of  the  bones  of  the  •  forea^-m.  Tlie 
bones  of  the  lower  row  decrease  from  without  inwards,  and  are  the  unciform, 
articulating  with  the  two  external,  the  os  magnum  with  the  large  internal,  and 
the  trapezoid  v»ith  the  small  internal  metacarpal  bones  ;  the  pisiform,  ter- 


.CAENIVORA THE    SKULL.  3  09 

minating  bluntly,  does  not  articulate  with  the  metacarpus,  the  pollex  or  thumb 
Ijeing  absent. 

The  metacarpal  hones  are  4  in  number.  The  middle  pair  are  large,  the  ?ide 
■pair  small ;  the  large  ones  articulate  with  each  other,  and  with  their  relative 
■small  ones  superiorly.  Each  terminates  distally,  as  the  single  one  of  the 
horse,  but  the  middle  pair  are  the  sole  weight-carriers,  for  the  lateral  ones  do 
•not  rest  upon  the  ground.  In  each  of  tlie  four  digits  <;h.ere  are  three  phalanges, 
Tvith  their  accessory  sesamoid  and  navicular  bones. 

PELVIS   AND   PELVIC    LIMB- 

The  OS  innominatum  presents  the  same  general  characters  as  that  of  the 
Tuminant ;  it  is,  however,  distinguished  by  the  form  of  the  ilium,  which  is  very 
-conve.x  on  its  anterior  border  and  crest,  and  by  the  absence  of  the  protuberance 
on  the  inferior  symphysis.  The  femur  differs  tittle  from  that  of  the  ox,  except 
in  its  more  contracted  neck,  which  is  about  on  a.  level  with  the  trochanter 
major ;  the  trochanter  minor  is  wanting.  The  tibia  resembles  that  of  the 
ruminant ;  its  anterior  tuberosity  is  notched,  and  the  external  malleolus  is 
supplied  by  the  distal  end  of  the  fibula.  The  fihala  extends  the  whole  len^tii 
of  the  tibia,  articulating  with  it  at  both  extreraitie-s  and  distally  with  the 
■astragalus  and  calcaneum.  The  tarsus  presents  no  important  deviation  from 
the  typical  joint,  except  -that  the  cuneiforme  medium  is  divided,  hence  there 
■are  in  the  lower  row  the  ecto,  meso,  and  endo-cuneiform  bones ;  the  distal 
articular  surface  of  the  astragalus  articulates  partly  with  the  cuboid  bone. 
The  metatarsus  and  phalanges  closely  resemble  those  of  the  anterior  limb. 
There  is  a  very  rudimentary  fifth  metatarsal  bone  on  the  inside,  a  rsstige 
probably  of  the  hallux  or  great  toe. 


CAENIVORA. 

In  this  order  our  descriptions  allude  mostly  to  the  Dog,  Uiat  animal  being 
an  excellent  type  of  the  order,  and  one  easily  obtained. 

Axial  Skeleton, 
the  skull. 
The  occipital  hone  of  the  Dog  is  very  strong,  and  triangular  behind,  termiim^ 
ting  in  a  sharp  pointed  crest.  The  tuberosity  is  not  well  marked  ;  the  styloid 
processes  are  short,  and  the  condyles  large.  The  foramen  lacerum  basis  crani? 
is  divided  into  two  portions  by  the  auditory  bulla,  which  is  large  aud  rounded  ; 
the  basilar  process  is  long  and'  thick.  The  Wormian  bone  is  united  to  the 
occipital  ;  the  ossifie  tentorium  is  large.  The  parietal  bones  are  very  convex, 
in  S'-me  breeds  meeting  in  a  sharp  ridge,  continuous  with  the  occipital  crest. 
The  frontal  tjones  are  triangular,  and  present  along  their  middle  a  hollow, 
moi-e  or  less  r.'ai'ked  The  orbital  process  is  simply  a  peak,  the  arch  being 
•complet'-.d  l.;p  a  ligament  ;  there  is  no  supraorbital  foramen  ;  the  frontal  bone 
articulates  sFich  the  cjperior  maxilla.  The  temporals  are  not  divisible  into 
distinct  pieces,  as  in  tJie  horse  ;  the  zygomatic  processes  are  large,  and  -project 
very  much,  forming  Capacious  temporal  fossse,  and  having  glenoid  ravities, 
which  are  elongated  transversely,  for  the  condyles  of  the  inferior  maxilla! 


110 


COMPARATIVE    OSTEOLOGY. 


SKELETON  OF  THE  DOG  (Carnivora). 
AxiAx  Skeleton. 


THE   SKULL. 

b.  Parietal,  2  :  c.  Frontal,  2 ; 


k,  Temporal.  2  ;.  Sphenoid,  1 ;. 


Cranial  Bones.— a.  Occipital    1 ; 
Ethmoid.  2  ;  Auditory  ossicles,  8. 

Facial  Bones.— f,  Nasal,  2  ;    e,  Iiachrymal,  2  ;    d,  Malar.  2 ;    h.  Maxilla.  2  ;    g,  Premaxilla,  2  r 
t,  Inferior  I-IaxiUa.  2  ;  Palatine,  2  ;  Pterygoid,  2  ;  Vomer,  1  ;  Turbinals,  4 ;      Hyaoia  series,  9. 
Teeth : — Incisors,  12  :  Canines,  4  ;  Molars,  26. 

Tlie  Trunk.— I  I,  Cervical  vertebrai,  7  ;  m  m.  Dorsal  vertebrse.  13  ;  n  n.  Lumbar  vertebrae,  7  \. 
0,  Sacrum  (three  segments),  \  ;  p  p,  Coccygeal  vertebrae  (variable),  20  ;  t  t,  Ribs,  26 ;  *  Sternum 
(eight  stemebrse),  1 ;  £  Costal  cartilages. 

Appendicular  Skeleton, 
pectoral  limb. 
u,  Scapula,  2 ;  v,  Humen^s,  2 ;  w,  Eadius,  2 ;  x,  ITlna.    Carpus  :— j/,  Trapezium,  2 ;  z,  Cunei- 
form, 2 ;  a',  Scaphoid,  2  ;  V,  Unciform,  2  ;  c'.  Magnum.  2  ;  d' ,  Trapezoid,  2  ;  e'.  Pisiform,  2  ;  Metar 
carpal  bones,  10  ;  K,  Anterior  sesamoids,  10 ;  g' ,  Posterior   sesamoids,  20.     Digit :— i'.  Proximal 
phalanges,  10;  V,  Median  phalanges,  8;  V,  Distal  phalanges,  10;  Small  sesamoids  wanting. 

PELVIC    LIMB. 

Pelvis. — Os  Innominatum  : — q,  Ilium,  2  ;  r,  Pubis,  2  ;  s,  Ischium.  2. 

The  Limb.—m'  Femur,  2;  o',  Fabellje,  4;  n',  PateUa,  2;  g'.  Tibia,  2;  p',  Tibial  sesamoid,  2; 
r',  Fibula,  2.  Tarsus  :— s',  Calcaneum,  2  ;  <',  Astragalus,  2  ;  u',  Cuboid,  2  ;  «>',  Superior  cuneiform,  2  :■ 
w\  Ecto-cuneiforme,  2  ;  x',  Meso-cuneiforme,  2  ;  2/',  Endo-cuneiforme,  2.  Metatarsus :— Large  bones, 
8 ;  z",  Small  bones,  2 ;  Anterior  sesamoid,  8 ;  Posterior  sesamoids,  16.  Digit :— Proximal  phalanges,. 
8 ;  Median  phalanges,  8  ;  Distal  phalanges,  8  ;  Small  sesamoids  wanting. 

Visceral  Skeleton. 
Os  Penis,  1 ;  Eudimentary  clavicle  (inconstant),  2. 

The  bones  of  the  Carnivora  Skeleton,  thus  considered,  are  345. 


CARNIVORA VERTEBRA.  Hit 

The  external  auditory  meatus  and  auditory  bulla  are  larj:;e,  the  sense  of  hearing 
in  carnivora  being  very  acute ;  there  are  only  diminutive  hyoid,  and  styloid 
processes.  There  are  two  canals,  of  which  there  exists  no  trace  in  other 
domestic  animals— viz.,  the  carotid,  which  traverses  the  mastoid  portion  to 
join  the  venous  canal  between  the  basilar  process  and  temporal  i  and  another 
which  pierces  the  petrous  portion  at  the  upper  part  of  tlie  carotid  canal,  and 
gives  passage  to  the  fifth  pair  of  nerves.  The  sphenoid  bone  resemhles  that  of 
man  ;  its  posterior  part  is  ^liort,  and  presents  two  large  wings,  which  mount  to 
the  temporal  fossae,  the  anterior  part  being  straight,  and  pi'olonged  by  small 
wings.  The  pterygoid  piocesses  are  very  short,  the  pituitary  fossa  limited  by 
Uie  clinoid  processes.  The  ctkmoicl  bone  presents  very  deep  fosste  and  well- 
developed  volutes. 

The  nasal  bones  are  small,  narrow,  but  wfc]er  in  front,  presenting  a  semi- 
•circular  concavity,  instead  of  a  peak.  The  superior  maxilla  is  short,  but  strong, 
differing,  as  all  the  facial  bones  do,  with  the  Breed;  it  articulates  by  a  long 
process  with  the  frontal,  forms  partly  the  socket  for  the  canine  tooth,  and  is 
spineless.  The  2^^'cmaxiUa  is  short,  and  presents  a  small  foramen  incisivum, 
which  is  often  wanting  in  the  cat,  alveoli  for  the  incisors,  an<l  an  ovul  incisive 
opening.  The  lachrymal  is  small,  and  in  the  cat  confined  to  the  orbital  cavity. 
The  malar  bone  articulates  in  the  usual  manner,  while  its  zygomatic  process  is 
large,  and  curved  outwards,  and  its  summit  bifid,  the  arches  being  formed  very 
similarly  to  those  in  the  omnivora.  The  palatine  bones  form  about  a  third  of 
the  palate  ;  they  do  not  assist  in  the  formation  of  the  sphenoidal,  but  furnish 
a  small  portion  of  the  maxillary  sinuses.  The  pterrjgoids  are  strong  and 
quadrilateral  Tlie  turbiyials  e.\tend  to  the  anterior  nares  ;  they  are  remark- 
able for  the  number  of  their  convolutions,  but  do  not  assist  in  the  formation  of 
the  frontal  and  maxillary  sinuses. 

The  inferior  maxilla  is  strong,  its  rami  broad  and  large,  presenting  a  deep 
depression  on  the  posteco-external  aspect,  in  which  is  inserted  the  masseter' 
muscle.  The  condyles  are  ovoid  transversely,  and  the  coronoid  processes  long 
and  broad,  the  sigmoid  notch  very  deep,  the  labial  foramen  double  or  triple, 
and  there  are  no  interdental  spaces.  There  is  a  tubercle  at  the  angle  for 
the  insertion  of  the  stylo-maxillaris  muscle.  The  symphysis  rarely  becomes 
ossified. 

The  hyoid  bone  is  triple— i.e.,  its  three  elements  do  not  unite.  It  has  two 
cornua  and  four  cornicula,  the  cornua  being  united  to  the  temporal  bones  by 
elastic  ligaments. 

VERTEBRA. 

The  true  vertebral  column  consists  of  27  segments— 7  cervical,  13  dorsal, 
and  7  lumbar.  The  cervical  vertebrcB  in  carnivora  are  proportionally  as  large 
as  those  of  the  horse.  The  atlas  possesses  large  and  expanded  alse  ;  a  groove 
or  notch  takes  the  place  of  the  anterior  foramen,  and  the  posterior  foramen  is 
present ;  the  posterior  articulation,  instead  of  being  flat,  has  glenoid  cavities, 
the  surface  inside  the  ring,  for  the  odontoid  process,  being  continuous  with 
them.  The  axis  is  long,  its  neural  spine  single  and  prominent,  overlapping 
and  sometimes  articulating  with  the  atlas,  thereby  completely  occluding  the 
atlo-axoid  space ;  the  odontoid  process  is  long,  convex  on  all  its  surfaces,  pointed 
anteriorly,  and  more  nearly  resembles  that  of  man  than  does  that  of  any  other 
domestic  animal ;    it  serves  as  a  pivot,  on  which  the  head  and  atlas  freely 


1  1  2  COMPARATIVE    OSTEOLOGY. 

r«late  ;  laterally  are  the  condyles  articulating  with  the  glenoid  cavities  of  thfr 
atlas.  The  remaining  cervical  vertebrae  diminish  as  they  proceed  backwards^ 
and  in  most  cases  have  large  neural  spines,  which  gradually  increase  from  the 
third  backwards. 

The  dorsal  vertehrce,  13  in  number,  vary  with  the  breed  ;  the  pedicles  coutaia 
large  posterior  notches  in  place  of  foramina.  The  spinous  processes  are  strong  ; 
the  four  or  five  anterior  ones  are  equal  in  height,  while  the  succeeding  ones 
decrease,  and  incline  backwards.  There  are  7,  sometimes  6,  strong  lumbar 
vertcbrce;  the  bodies  are  compressed  from  above  downwards,  the  posterior 
notches  are  large,  and  the  neural  spines  incBned  forwards.  The  transverse 
processes  slope  downwards  and  forwards  ;  the  anterior  articular  processes 
expand  laterally,  receiving  between  them  the  posterior  ones  of  the  contiguous- 
vertebra.     These  vertebrae  possess  anap(Jphyses  diminishing  backwards. 

The  sacrum  usually  consists  of  3  segments,  and  is  frequently  as  broad  behind 
as  in  front ;  the  first  segment  resembles  the  last  lumbar.  The  sacral  spine  is 
thin,  and  serrated  superiorly  ;  the  transverse  processes  are  bifid,  consisting  of 
upper  and  lower  portions,  the  upper  resembling  those  of  the  lumbar  region. 
The  coccygeal  bones  vary  from  16  to  21,  the  anterior  ones  having  the  character* 
of  true  vertebra;. 

There  are  usually  13  pairs  of  ribs,  9  true  and  4  false  ;  their  size  and 
curvature  vary  much,  but  they  are  usually  somewhat  thick  and  straight. 
The  sternum  consists  of  8  elongated  cylindrical  sternebree,  which  resemble 
somewhat  in  form  the  terminal  coccygeal  bones  of  the  horse. 


Appendicul,\r  Skeleton, 
pectoral  limb 

The  scapula  is  very  large,  the  spine  being  almost  central,  and  terminating 
inferiorly  in  an  acromion  process,  which  descends  close  to  the  gleiioid  cavity, 
where  it  curves  backwards.  The  cartilage  of  prolongation  is  wanting.  The 
hximcrus  is  long,  slender,  considerably  curved,  but  not  much  twisted  ;  the 
external  trochanter  is  well  developed,  the  internal  almost  wanting;  the  bicipital 
groove  is  single.  The  condyles  are  large,  and  the  coronoid  and  intercondyloid 
fossre  united,  but  not  always,  by  a  canal  which  penetrates  the  bone.  In  the 
Felidee  there  is  a  supracondyloid  foramen,  situated  above  the  internal  condyle, 
between  the  humeral  shaft  and  an  outer  plate  of  bone.  The  radius  and  ulna. 
are  about  equal  in  volume,  the  ulna,  if  anything,  being  the  larger  ;  these  bones 
articulate  with  each  other  solely  by  their  extremities,  above,  by  an  articular 
concave  facet  on  the  ulna,  and  a  convex  one  on  the  radius  ;  below,  by  a  concave 
facet  on  the  radius  and  a  convex  one  on  the  ulna  ;  the  two,  as  it  were,  cross 
each  other,  the  upper  extremity  of  the  ulna  articulating  behind  and  to  the 
inner  side,  the  lower  extremity  to  the  outer  side.  i 

The  bones  of  the  carpus  are  7.  The  upper  are  the  scaphoid  and  lunar  united^ 
the  cuneiform,  and  trapezium  ;  the  remainder  correspond  mostly  with  those 
nf  the  hog.  , 

There  are  5  metacarpal  bones,  4  large  and  1  small.  The  digits  of  the  former, 
jiomologues  of  the  four  fingers  of  man,  have  three  phalanges  each,  and  two 
sesamoids,  thS  third  sesamoid  bone  being  replaced  by  a  ridge  on  the  third 
phalanx.    The  fifth  and  most  internal  digit  has  only  two  phalaiiges,  the  m^diau 


CARNIVORA' — PELVTS    AND    PELVIC    LIMB. 


113 


phalatiX  being  wanting ;  it  co.Tesponds  to  the  human  poUex  or  thumb.  Between' 
each  metacarpal  bone  and  its  proximal  phalanx  we  have  anteriorhj  a  very  small 
sesamoid  bone. 

PELVIS   AND    PELVIC   LIMB. 

The  pelvic  cavity  is  generall;:  long  and  narrow,  but  the  ossa  innominata  are! 
very  strong;  the  iliac  spines  and  crest  present  a  continuous  tiiick  rounded! 
ridge.  The  ischium  is  also  thick  and  strong,  tlie  ischiatic  spiiie  and  tuberosity, 
becoming  one  tubercle.  The  otyloid  cavity  is  surrounded  by  a  prominent 
border,  slightly  notched  within. 

The  femur  is  straight  and  long,,presenting  a  prominent  neck,  and  a  muscular' 
line  posteriorly,  equivalent  to  the  linea  aspe.ra  oi  man.  The  supracondyloid 
fossa  is  represented  by  a  small  tubercle.  Above  6ach  condyle  is  a  small  facet, 
articulating  with  a  sesamoid  bone  ;  these  two  bones  are  called  the  fabellce,  or 
gastrocnemic  sesamoids.  | 

The  tibia  andfihila  are  long,  and  united  in  ths  inferior  half  of  their  middle 
by  ligaments,  at  either  extremity  by  articulation  ;  the  fibula  also  articulates 
^with  the  astragalus,  thus  supplying  the  external  malleolus  to  the  tibia.  There 
iis  a  small  sesamoid  bone  at  the  external  part  of  the  head  of  the  tibia. 


■JK    IV 


Fig  32., 
A,  Hand  or  Anterior  Foot  of  the  Dog  ;  B,  That  of  the  Hog  ;  C.  That 
of  the  Elk;  D,  That  of  the  Ox.    I.  Pollex  .;^  II    Index;  III.  Medius;) 
.IV.  Annulus  :  V.  Minimus. 


The  tarsus  consists  of  7  bones,  as  in  the  hog — viz.,  the-calcaneum,  astragalus,^ 
cuboid,  and  four  cuneiforms,  a  superior  one  corresponding  to  the  magnum  of  i 
the  horse,  and  three  in  a  row  below  it,  the  ecto,  meso,  and  endo-cuneiforras,  | 
The  astralagus  presents  distally  a  distinct  head,  separated  by  a  neck,  which 
articulates  with  the  cuneiforme  magnum. 

The  metatarsal  bones  are  '  large  and  1  rudimentary,  the  large  ones  each 
teiminating  in  three  phalanges,  with  their  accessory  sesamoids,  as  in  the 
anterior  limb  ;  the  fifth,  or  small  rudimentary  metatarsal,  homologous  with  the 

I 


114  COMPARATIVE    OSTEOLOGY. 

hallux  of  man,  is  very  generally  only  a  ligamentous  cord,  in.  which  is  found  ; 
short  bone,  which  represents  a  phalanx. 


Fig.  33.  Fig.  34. 

Clavicle  of  a  Dog— enlarged  one-half.  Clavicle  of  a  Cat— natural  size. 

VISCERAL   SKELETON. 

In  carnivora,  generally  speaking,  there  is  a'davicle,  but  it  is  incomplete,  and 
is  found  embedded  in  the  soft  structures  between  the  sternum  and  shoulder. 
In  the  dog  it  is  often  represented  by  a  piece  of  ligamentous  tissue,  and  when 
it  does  exist  as  a  bone,  it  is  very  small  and  somewhat  triangular  in  shape. 

The  Felidae  or  cat  tribe  possess  a  clavicle  which,  to  a  certain  extent, 
resembles  in  shape  that  of  the  human  subject,  being  elongated,  rounded,  and 
slightly  curved.  Occasionally  this  bone  in  the  cat  is  continued  by  ligaments, 
•which  unite  it  both  to  the  sternum  and  to  the  acromion  process. 

Os  Penis. 

This  is  a  .single  bone  very  generally  found  in  the  penis  of  the  carnivora,  and 
alVvays  in  the  dog  ;  in  the  cat  it  is  said  to  be  less  persistent,  and  when  present 
much  smaller.     It  is  a  thin  piece  of  bone  hollowed  to  form  a  longitudinal 


6 

Fig   35. 
Os  Penis  of  a  Dog,  half  the  size  of  that  of  a  large  animal. 
a  a.  Inferior  groove  ;  6,  Anterior  end  .  c,  Posterior  end. 

groove,  in  which  the  uretha  lies  ;  the  groove  ceases  anteriorly,  and  at  this 
extremity  the  bone  becomes  flat  and  pointed.  Both  extremities  are  prolonged 
by  cartilages. 

RODENTIA- 
This  large  order  we  have  already  mentioned  as  being  characterised  by  its 
peculiar  dentition.     One  representative  of  the  order  is  the  common  Rabbit, 
>vhich  belongs  to  the  family  Leporidse. 

Axial  Skeleton. 

There  are  12  dorsal,  7  lumbar,  and  4  sacral  vertebrae.  The  wing  of  the 
ctlas  presents  no  foramina  externally,  but  there  is  a  very  large  notch  in  its 
anterior  border,  inside  which  is  the  cerebro-spinal  foramen.  As  in  the 
carnivora,  there  is  no  atlo-axoid  space.  The  centra  of  the  cervical  vertebrce 
are  short,  broad,  and  strong ;  while  those  of  the  dorsal  region  gradually 
increase  in  length  backwards.      The  lumbar  vertebrce  are  largely  developed, 


AYES  115 

their  transverse  processes,  long  and  slender,  being  directed  downwards  and 
forwards  ;  the  articular  processes  are  almost  as  prominent  as  the  neural  spines, 
the  prominent  portions  beiiig  termed  the  mammillary  processes  (meta- 
pophyses),  and  they  may  be  traced  anteriorly  into  the  dorsal  region  ;  they 
.give  attachment  to  portions  of  the  longissimus  dorsi  muscle.  The  anterior 
costal  tubercles,  prolonged  and  sharpened,  likewise  afford  attachment  to  that 
muscle.  The  sfernebrce  are  five  in  number,  the  presternum  being  very  long 
and  cariniform  in  shape. 

In  the  skull  we  note  the  unusual  length  of  the  zygomatic  process  of  the  malar 
bone,  and  absence  of  a  frontal  arch,  which  is  represented  by  a  short  bifid  process. 
The  optic  foramina  unite  to  form  a  single  passage  leading  from  one  orbital 
fossa  to  the  other.  The  diastema  and  incisive  openings  are  both  very  large, 
and  laterally  the  superior  maxilla  is  incompletely  ossified,  giving  an  irregular 
cribrated  appearance  to  the  bone  ;  the  bony  palate  is  exceedingly  short.  The 
auditory  bulla  and  external  meatus  are  well  marked.  The  long  axis  of  the 
ina,x\\la,vj  condyle  is  placed  longitudinally,  and  the  coronoid  process  is  very 
small  and  far  below  the  level  of  the  condyle,  while  at  the  angle  of  the  jaw 
there  is  a  prominent  roughened  ridge  or  spine.  There  are  no  canine  teeth, 
and  two  chisel-shaped  incisors  exist  in  each  jaw  ;  in  the  upper  jaw  of  the 
rabbit  and  hare  there  are  also  two  very  small  incisors  placed  immediately 
behind  the  large  ones. 

Appendicular  Skeleton. 

The  scapula  has  a  very  large  acromion  process  which  projects  backwards, 
arching  over  the  postea-spinatus  fossa.  There  is  a  small  clavicle, but  it  is 
incomplete.  The  coronoid  and  condyloid  fossae  of  the  humerxis  are  connected 
by  a  foramen.  The  ulna  is  complete,  reaching  to  the  carpus,  but  there  is  no 
motion  between  it  and  the  radius,  and  the  extremity  is  therefore  prone.  There 
are  five  digits,  one  of  which  represents  the  poUex  or  thumb.  The  pelvis  is 
broad  and  shallow,  the  ischial  arch  deep,  and  the  obturator  foramen  large. 
H\\Q  femur  has,  like  that  of  the  horse,  a  third  or  minor  trochanter  ;  also  two 
well-marked  fabellse.  The  tibia  and  fibula  are  anchylosed,  the  former  bone 
being  very  long.  The  astragalus  resembles  that  of  the  carnivora.  There  are 
five  digits,  including  the  hallux. 


AVES. 

The  scope  of  the  present  work  will  allow  only  very  brief  treatment  of  this 
part  of  the  subject.  We  shall,  therefore,  merely  name  a  few  of  those  features 
in  which  the  skeleton  of  the  bird  differs  in  a  marked  manner  from  the 
mammalian  type. 

The  vertebrae  vary  greatly  in  number,  the  cervical  in  some  classes  number- 
ing over  20,  and  never  less  than  8.  Small  cervical  ribs  exist  in  the  young 
animal,  which  in  age  may  become  anchylosed  to  the  vertebrae,  and  in  the 
dorsal  region  osseous  splints  unite  the  successive  transverse  processes.  On  the 
posterior  edge  of  each  rib,  except  the  first  and  last,  is  a  process  called  the  pro- 
cessus uncinatus,  which  overlaps  the  succeeding  rib.     The  sternum  is  a  single 


116 


COMPARATIVE   OSTEOLOGY. 


Fia.  36. 
Skeleton  of  a  Bird,    o,  Radius  and  Ulna ;  h.  Dorsal  vertebrae  :  c,  Sacrum 
and  Pelvis ;  g,  Ploughshare  bone  ;  k,  Tibia ;  i.  Metatarsus :  d,  Furculum  ; 
e,  carina  of  the  Sternnm;  /,  Distal  phalanx  of  pectoral  limb. 


Sternum  of  a  Bird.      A,  Lateral  aspect:    B,  Inferior  aspect;    r,   Rostrum ; 
c.p.  Costal  process;   pl.o,  I'leurosteon  ;  c,  Carina;  in.x,  Middle  Xiphoid,  process^ 


AVES. 


117 


bone  presenting  a  very  large  central  process  posteriorly,  the  central  xipheid 
process  (lophosteon),  outside  which  is  a  large  bifurcated  process  (metosteon),  the 
two  projections  of  which  are  called  the  median  and  external  xiphoid  processes, 
and  antero-laterally  is  the  ridge  (pleurosteon),  which  gives  attachment  to  the 
ribs.  The  inferior  edge  of  the  central  ridge  is  called  the  carina;  often  a 
small  median  spine  exists  anteriorly,  the  rostrum  or  presternum. 

The  following  Table  shows  the  ntimber  of  vertebral  segments  usually  found- 
in  domesticated  birds : — 


Rasores, 


Natatores, 


Cervical. 

Pigeon, . 

.     ,     12 

Fowl,     . 

:,      ,       14 

Duck,    . 

.     .      15 

Goose,  . 

cv     ^      18 

Dorsal.      "t^umbo-Sacral.    Coccygeal. 


i      '     \ 


The  costal  cartilages  are  ossified,  and  thus  birds  are  said  to  possess  sternal 
and  vertebral  ribs.  Some  of  the  lumbar  and  coccygeal  vertebrae  become 
anchylosed,  and  assist  in  forming  the  sacrum;  it  is  not  indeed  easy  to  define 
the  exact  points  of  demarcation  between  the  lumbar,  sacral,  and  coccygeal 
regions.    The  coccygeal  bones  terminate  in  an  expanded  segment,  termed  the 


Fig.  3S. 
Skull  of  &  fowl.  "A,  Inferior  aspect,  the  mandible  being  removed  ;  B,  Lateral  aspect ; 
px,  Premaxilla;  mx,  Superior  maxilla;  p.  Palatine  bone;  v,  Vomer;  j,  Jugal  bone; 
qj,  Quadrato-jugal  bone;  I,  Lachrymal;  me.  Median. ethn?oid  ;/,  Frontal  ;  pf,  Post-fronta) 
process  ip,  Parietal ;  pt.  Pterygoid  ;  q,  Os  quadratum  ;  S2,  Squamosal ;  eu,  Process  before  the 
Eustactdan  aperture ;  ho,  Basi-occipital,  and  so,  Supra-occipital  bones ;  ar,  Articular, 
a,  Surangular,  and  d,  Dentary  portion  of  the  Mandible. 


ploughshare  bone.  In  the  skull  we  have  to  note  chiefly  the  absence  of  teeth^ 
the  existence  of  only  one  occipital  condyle,  and  the  articulation  of  the  man- 
dible or  lower  jaw,  which  does  not  articulate  directly  with  the  skull  above,, 
but  there  is  interposed  the  quadrate  bene,  which,  when  the  lower  jaw  is; 
depressed,  acts  on  a  process,  the  quadrato-jugal  bone,  connecting  it  with  the 
maxilla,  and  so  simultaneously  raises  the  upper  jaw,  there  being  usually  cl^Thti 
vertical  motion  between  the  latter  and  the  cranium. 


118 


COMPARATIVE    OSTEOLOGY. 


The  pectoral  arch  consists  of  three  parts — the  scapula,  clavicle,  and  coracoii^ 
bone.  The  scapula  is  sword-shaped,  and  placed  nearly  horizontally ;  the 
■coracoid  bone,  the  strongest  of  the  three,  is  almost  perpendicular,  and  firmly 
attached  to  the  sternum  below,  affording  a  strong  basis  for  the  bones  of  the 
wing  to  move  upon  ;  it  helps  to  form  the  glenoid  cavity  for  the  humeras.  The 
clavicles  project  downwards  and  slightly  forwards,  arching  inwards,  and 
generally  becoming  united  below  to  form  a  flattened  plate,  the  hypochideum  / 
^he  united  clavicles  are  termed  the  furculum.,  familiarly  known  as  the  "  merryw 

thought."  The  hypocleiueum  is 
usually  joined  by  a  ligament  to  the 
sternum  below ;  in  seme  clnsses  of 
birds  it  is  absent ;  in  some  the 
clavicles  are  not  united  ;  in  some, 
again  they  are  united  by  ossification 
to  the  sternum.  The  ubia  is  larger 
and  stronger  than  the  radius;  the 
carpus  consists  of  two  bones,  the 
metacarpus  of  three,  one  of  which 
33  a  rudimentary  pollex.  There  are 
two  digits,  one  of  which  has  one,  the 
other  two  or  three  phalanges. 

The  pelvis  is  expanded  and  shield- 
like, -and  consists  of  the  ilium, 
ischium,  and  pubis ;  but  there  is 
no  inferior  symphysis,  and,  therefore,  no  true  pelvic  cavity.  The  pubis  is 
styliform,  and  directed  backwards  and  inwards  ;  in  the  ostrich  alone  it  articu- 
lates with  its  fellow.    The  femur  is  short,  the  tibia  long,  and  anchylosed  with 


Fio.  39. 
^    Pectoral  arch  of  a  Bird,    sc,  Scapula;  co,  cora- 
eoid  bone  ;  /,  Clavicles,  terminating  below  in  the 
hypocleideum ;  gl.  Glenoid  cavity. 


Pelvis  of  a  Bird 
Acetabulum. 


A.  Superior :  B,  Lateral  aspect :  sm,  Sacrum  :  II,  Ilium ;  Is,  Ischiv 


A.VES.  IW 

the  fibula,  which  is  sman._  The  tarsus  is  early  fused  with  the  metatarsus,  the 
latter  consisting  generally  of  one  long  bone.  The  digits  vary  in  number ;  the 
domesticated  birds  usually  have  three  anteriorly  and  the  hallux  postero-inter^ 
nally  ;  the  outermost  has  five  phalanges,  the  next  four,  the  next  three,  while  the 
hallux  has  only  two.  The  spur,  a  horny  projection  from  the  metatarsus,  i» 
sometimes  counted  as  a  digit. 

The  bone  tissue  of  birds  is  exceedingly  compact  and  hard,  and  white  in 
colour;  and  some  of  the  bones  are  pneumatic,  or  contain  air  instead  of  marrow; 
notably  these  are  the  bones  of  the  skull,  the  sternum,  and  the  proximal  bonea 
of  the  limbs.  There  is  great  variety  in  the  amount  of  pneamaticity  possessed 
by  the  skeleton  in  different  species,  but  it  is  not  necessarily  guided  by  tha, 
Jlying  power  of  the  animal. 


CHAPTER  II. 

AETHROLOGY, 

The  several  bones  which  form  the  skeleton  are  united  by  means 
of  certain  soft  structures,  forming  a  series  of  articulations  or 
joints,  the  study  of  which  is  termed  Arthrology  or  Syndesmology. 

Before  considering  the  different  forms  of  joints,  it  will  be  advis- 
able to  describe  briefly  the  various  tissues,  other  than  bone,  which 
enter  into  and  contribute  to"^ards  their  formation.  These  are 
.chiefly  cartilage,  connective  and  elastic  tissues,  and  fat. 

In  health,  one  bone  never  comes  directly  in  contact  with  another, 
cartilage  or  fibrous  tissue  being  always  interposed ;  an  exception  to 
this  exists  in  the  adult  skull,  most  of  the  bones  of  which  become 
firmly  united  by  ossification  of  the  interposed  soft  material. 

CARTILAGE. 

Cartilage,  known  also  by  the  familiar  name  of  gristle,  is  a  firm, 
bluish-white,  elastic  animal  substance,  somewhat  translucent, 
resilient,  and  flexible,  possessing  great  cohesive  power.  That 
which  forms  the  original  basis  of  the  bony  framework  is  termed 
temporary,  and  that  which  persists  in  the  adult,  pei^manent 
cartilage  ;  the  former  disappears  as  it  is  replaced  by  bone,  but 
the  latter,  of  which  alone  we  have  to  treat  here,  never  under 
normal  circumstances  becomes  ossified.  Cartilage  consists  of 
corpuscles  or  cells,  usually  imbedded  in  an  intercellular  substance 
or  matrix.  The  cells,  which  are  contained  in  lacunae  in  the  matrix, 
are  oval,  round  or  fusiform,  and  nucleated,  the  nuclei,  which 
appear  under  the  microscope  as  small  spots,  containing  still 
smaller  objects  called  nucleoli.  Cartilage  when  boiled  yields 
chondrine,  a  substance  varying  slightly  from  gelatine. 
■  There  are  three  varieties  of  the  permanent  kind — hyaline, 
Jibro,  and  cellular  cartilage.  In  the  first,  the  matrix  is  homogen- 
eous, or  void  of  definite  structure,  appearing  slightly  granular  under 
120 


CARTILAGE. 


121 


the  microscope.  Fibro-cartilage  is  characterised  by  a  matrix  of 
fibrous  tissue  ;  while  the  cellular  variety  consists  of  an  aggrega- 
tion of  cells  without  a  matrix. 

Hyaline  cartilage  is  distinguished  by  the  following  names, 
according  to  the  purpose  it  serves  : — Articular,  when  it  encrusts 
the  articular  surfaces  of  bones,  helping  to  form  joints  by  supplying 
a  smooth  elastic  cushion,  which  diminishes  both  concussion  and 
friction  ;  Costal,  when  it  supplies  elastic  prolongations  (hsemapo- 
pbyses)  to  the  ribs,  connecting  them  distally  with  the  sternum  ; 
Memhraniform,  when  it  appears  as  thin  plates,  forming  per- 
manently open  tubes, — the  trachea  or  wind-pipe  is  composed  of 
this  kind  of  cartilage. 

In  articular  or  encrusting  cartilage  the  matrix  is  abundant, 
and  the  cells  vary  in  form,  those  near  the  surface  being  flatter 
and  more  numerous.  It  is 
always  thickest  in  the  young, 
becoming  thinner  as  the  sub- 
jacent ossification  proceeds.  It 
is  thickest  in  the  centre  of 
convexities,  thinnest  in  the 
centre  of  cavities.  In  the  adult 
it  is  non- vascular,  being  nour- 
ished by  a  vascular  zone  in 
the  synovial  membrane,  called 
the  circulus  articuli  vasculosus, 
from  which  the  nutritive  ma- 
terial is  conveyed.  The  blood- 
vessels of  the  bone  underneath  the  cartilage  also  assist  inl 
supplying  nourishment  to  the  latter.  All  hyaline  cartilage, 
except  the  articular  kind,  is  covered  by  a  membrane  called  the 
perichondrium. 

Fibro-cartilage  consists  of  cartilage  cells  and  fibrous  tissue, 
which  may  be  white  or  yellow,  the  former  being  tough  and  strong, 
the  latter  highly  elastic.  White  fibro-cartilage  is  much  the  more 
plentiful,  and  presents  the  following  varieties  : — It  ^is  called  Inter- 
articular  when  it  appears  as  a  pad  interposed  between  the  two 
articular  cartilages  which  form  a  joint ;  such  a  pad  is  termed  a 
meniscus,  and  the  temporo-maxillary  and  femoro-tibial  joints  arei 
furnished  with  such.  Circumferential,  where  it  surrounds  andi 
•deepens  an  articular  cavity,  as  the  acetabulum.  Connecting,) 
when  it  is  interposed  between  bones  and  firmly  connects  them,  asl 


Fig.  41. 
Section  of  hyaline  cartilage,    a,  Four  separating'; 
cells  ;   6,  Two  cells  in  apposition  ;  c  c.  Nuclei ; ' 
d,  Cavity  in  the  matrix  containing  three  cells. 


122  ARTHROLOGY. 

between  the  vertebral  ceutra.  Sirat'iform  or  InvesHvg,  wlifu  it 
clothes  the  parts  of  bones  over  which  the  tendons  of  muscles  phy, 
sometimes  existing  in  the  tendons  themselves. 

This  tissue  is  dullish  white,  opaque,  and.  for  the  most  part, 
devoid  of  perichondrium  i  it  is  vascular,  but  its  blood -vefisels  are 
few,  and  confined  to  the  fibrous  tissue,  which  exists  as  inlerwoven 
bundles  of  fil)res.  with  ca.rtilage  cells  interspersed  amongst  them. 
In  the  variety  connecting  vertebrae,  it  consists  of  concentric  rings 
of  fibrous  tissue,  enclosing  a  soft  elastic  centre,  partly  made  up  of 
cartilage  cells,  and  often  regarded  as  the  remnant  of  the  notochord. 
In  fishes  this  portion  is  soft  and  pulpy,  filling  the  oppcjsing  con- 
cavities of  the  vertebral  centra.  Its  power  of  cohesion  is  verj* 
great,  surpassing  even  that  of  bone. 

Yellow  eladic  fihro-cartilage  is  found  in  the  epiglottis  or  valve, 
which  closes  the  principal  air-tube  ;  it  forms  part  of  the  frame- 
work of  the  ear.  and  of  the  Eustachian  tubes  which  convey  air 
to  the  tympanum.  The  fibres  forming  the  matrix  are  similar  to 
those  of  yellow  elastic  tissue. 

Cellular  or  rethular  cartilage  is  found  in  the  *;ar  of  some 
small  rodents,  and  in  the  bat.  It  consists  of  cells  derisaly  packed, 
and  apparently  without  a  matrix :  the  walls  of  the  cells  thus 
coming  into  contact,  give  it  a  net- like  appearance,  hence  the 
name  reticular  cartilage, 

CONNECTIVE   TISSUE. 

In  one  form  or  other  this  tissue  is  found  in  hW  parts  of  the 
body.  The  chief  varieties  are  the  areolar  and  the  fibrous ;  the 
former  serving  as  a  connecting  medium,  and  support  to  the  various 
organs,  and  to  the  structures  of  which  they  are  formed.  It 
appears  as  a  loose  translucent  mesh,  its  interwoven  bundles  form- 
ing spaces  termed  the  areolae  or  cells,  hence  its  name  Cellular  or 
Areolar  Tissue.  It  consists  of  minute  laminae  and  filaments 
mixed  with  small  fibres  of  elastic  tissue,  while  cells,  or  their 
remains,  nuclei  and  walls,  are  also  present,  the  whole  embedded 
in  a  perfectly  transparent  basis.  Other  slightly  varying  forms, 
are  termed  Retiform,  Gelatinous,  &c.,  while  the  connective  tissue, 
of  the  brain  and  retina  has  received  the  name  of  Neuroglia. 

White  fibrous  tissue  has  a  similar  structure  to  the  above,  but 
is  dense,  strong,  and  practically  non-elastic.  The  filaments  which 
form  it  are  mostly  parallel  and  wavy  in  their  arrangement.      It 


ADIPOSE    TISSUE. 


12a 


S'MrJ^.ii  kUjjTii^-/,^k 


White  fibrous  tissue  from  a  ligament. 
65  diamrs. 


appears  in  two  forms — the  sheeted  or  aponeurotic;,  which  is  found  in 
investing  ligaments,  membranes,  periosteum,  &c.  ;  and  the  cordi- 
form,  in  which  the  fibres  are  col- 
lected in  strong  bundles ;  this  is  the 
chief  constituent  of  the  binding 
ligaments,  which  hold  articulating 
bones  together  and  limit  their  mo- 
tion. The  tendons  of  muscles  are 
also  made  up  mostly  of  this  kind 
of  tissue,  but  both  in  them  and  in 
ligaments  yellow  elastic  fibres  are 
also  found. 

Connective  tissue  contains  nerves 
and  blood-vessels,  for  the  supply  of 
neighbouring  structures  as  well  as  for 
its  own  nourishmeut,  and  also  tendon  cells,  the  latter  lying  in 
the  spaces  betweeu  the  smaller  bundles.  "When  healthy  this 
tissue  is  little  sensitive  to  pain. 

YELLOW   ELASTIC    TISSUE. 

This  differs  from  the  white  tissue  in  being  yellow,  elastic,  and 
not  so  tough  or  strong.  Its  fibres  are  sometimes  as  large  in  dia- 
meter as  4^^QQ  in.;  but  when  mixed  with  white  tissue  in  tendons 
the  diameter  may  not  be  more 
than  one-sixth  of  this.  The 
fibres  branch  and  join  each 
other,  and  their  ends  curl  up 
when  cut  or  broken.  Acetic 
acid  has  no  effect  on  the  yellow 
tissue,  while  it  causes  fibres  of 
the  white  to  swell  greatly  and 
become  quite  transparent ; 
again,  when  white  tissue  is 
boUed  gelatine  is  obtained, 
which  is  not  the  result  of  boil- 
ing the  yellow  fibres. 

Yellow  elastic  tissue  is  found  nearly  pure  in  the  ligamentum 
Quchse,  the  tunica  abdominis,  the  coats  of  the  largest  arteries,  and 
elsewhere.     The  lungs  contain  a  large  quantity  of  this  tissue. 

AriPOSE   TISSUE.. 

Fat  or  adipose  tissue  consists  of  cells  containing  an  oily  material, 
and  arranged  in  isolated  groups,  or  slightly  separated  by  meshes 


Fio.  IS. 
Yellow  elastic  tissue,  magnified,  from  the  liga- 
mentum nuchas  of  a  calf.    65  dian'rs. 


124 


ANTHKOLOGY. 


Fio.  44. 
Adipose  tissue  magnified. 
n  a,  Fat  cells — those  on  the 
right  in  mass ;  those  on  the 
left  spread  amongst  the  con- 
nective tissue  fibree  b  6. 


of  areolar  tissue  and  capillary  blood-vessels.  It  is  found  in  many 
parts  of  the  body,  and  varies  greatly  in  quantity ;  in  joints  it 
occurs  between  the  ligaments,  and  serves 
the  purpose  of  a  packing  material,  while 
in  the  form  of  medulla  or  marrow  it 
occupies  the  cavities  of  bones.  In  fat 
cells  a  nucleus  is  rarely  visible,  without 
special  preparation. 

LIGAMENTS. 

Ligaments  are  dense,  fibrous,  connecting 
structures.  They  exist  in  most  articula- 
tions, and  are  made  up  principally  of  white 
fibrous  tissue.  There  are  two  kinds — 
caijsular  or  bursal,  and  funicular  or 
binding  ligaments. 

Capsular  ligaments  are  membranous 
structures,  generally,  but  not  always,  en- 
closing true  joints.  They  consist  of  a  dense  interlacement  of 
fibres  attached  to  bones,  round  the  edges  of  the  articular  cartil- 
ages, partially  or  wholly  surrounding  the  joint ;  some  regard 
them  as  a  continuation  of  the  periosteum.  They  are  never 
closely  applied,  their  use  being  to  form  cavities  round  the  joints, 
enclosing  and  protecting  the  synovial  or  lubricating  apparatus 
inside. 

Funicular  or  binding  ligaments  consist  of  rounded  or  flattened 
cords,  or  bands  of  fibrous  tissue,  passing  from  one  bone  to  another, 
firmly  attached  to  roughened  portions  of  their  surfaces.  They 
hold  the  bones  in  their  places,  at  the  same  time  allowing  the 
requisite  amount  of  motion  in  the  joints.  Ligaments  which  are 
situated  between  bones  are  often  termed  interosseous.  Annular 
ligaments  are  those  which  bind  down  and  protect  the  tendons  of 
muscles  in  certain  joints,  converting  grooves  in  the  bones  into 
channels  or  tubes  which  are  lined  with  synovial  membrane,  and 
through  which  the  tendons  play. 

Some  ligaments  are  composed  almost  entirely  of  yellow  elastic 
tissue,  such  as  the  ligamentum  nuchae  and  the  ligaments  con- 
necting the  vertebral  arches. 

SYNOVIAL   MEMBRANES. 

These  are  thin  membranes  lining  the  capsular  or  binding 
ligaments   of    true   joints,   or   they   are   interposed    elsewhere 


CLASSES   OF  JOINTS.  125 

between  structures  whicli  move  one  upon  another,  and  which 
would  otherwise  be  injured  by  the  friction.  They  resemble 
what  are  termed  serous  membranes,  in  lining  closed  cavities, 
and  in  containing  a  layer  of  endothelial  cells  which  secrete  a 
a  lubricating  fluid,  called  synovia  or  joint-oil ;  the  foundation  of 
these  membranes  is  a  layer  of  connective  tissue,  which  varies 
■considerably  both  in  density  and  thickness. 

The  synovial  membrane  terminates  at  the  border  of  the  articu- 
lar cartilage,  which  in  the  adult  it  never  covers  ;  in  the  foetus  it 
is  said  by  some  authorities  that  it .  covers  the  cartilage  also. 
Near  the  borders  of  articular  cartilages  the  membrane  is  generally 
found  as  a  projecting  fold,  the  projection  being  due  to  a.  small 
pad  of  fat,  interposed  between  the  membrane  and  the  capsular 
ligament.  These  projections  were  once  erroneously  termed 
synovial  glands,  but  their  use  is  probably  to  assist  in  forcing  the 
synovia  between  the  opposing  surfaces  of  cartilage. 

Under  the  cellular  layer  blood-vessels  are  found,  and  near  the 
articular  cartilage  there  is  formed  a  vascular  zone,  the  circulus 
articuli  vasculosus,  in  which  the  capillaries  terminate  by  dilated 
loops  ;  articular  cartilage  derives  its  nourishment  partly  from  this 
source  (see  page  121). 

There  are  three  forms  of  these  membranes : — the  capsular, 
which  line  the  capsular  ligaments  of  all  true  joints;  bursal  mem- 
branes, found  where  one  structure  moves  upon  another,  as  when 
a  tendon  plays  over  a  bone,  aod  known  as  synovial  hiirsce ; 
or,  when  they  exist  in  the  subcutaneous  tissue,  between  the 
skin  and  certain  prominent  parts  of  the  skeleton,  they  are  known 
as  hursce  mucosce.  The  third  form,  %'aginal  nnenihranes  or  sheaths, 
exist  where  one  tendon  forms  a  sheath  for  another,  or  in  other 
canals  through  which  tendons  glide. 

Synovia-  or  joint  oil,  is  a  viscid,  transparent  fluid,  colourless, 
or  pale  yellow,  physically  resembling  oil,  but  it  contains  very 
little  fatty  material,  consisting  chiefly  of  albumen,  salts,  and 
water  ;  it  is  secreted  by  the  ceils  on  the  inner  surface  of  the 
membrane.  When  an  animal  is  in  active  exertion,  there  is  a 
greater  demand  for  joint  oil  than  when  at  rest,  consequently  there 
is  an  increased  secretion  of  it. 

CLASSES    OF    JOINTS. 
Joints    may   be    divided    into    three    classes — Immovable    or 
Synarthrodial,   Movable  or  Diarthrodial,  and  Mixed  or  Amphi- 
arthrodial. 


126  ARTHROLOGY, 


SYNARTHROSIS. 


lu  an  immovable  joint  there  is  only  a  thin  layer  of  fibrous  or 
cartilaginous  material  interposed  between  the  bones,  the  fibrous 
layer  of  the  periosteum  of  both  bones  uniting  to  cover  and 
become  attached  to  the  connecting  material,  thus  serving  as  a 
ligament.  If  the  connection  is  fibrous,  the  joint  i&  generally  called 
a  suture ;  if  cartilaginous,  a  synchondrosis,,  These  joints  are 
found  chiefly,  but  by  no  means  solely,  in  the  skull :  and  they 
tend  to  become  obliterated,  in  the  adult,  by  ossification  of  the 
connecting  material.  The  varieties  of  synarthrosis  are  the  sutura. 
synchondrosis,  schindylesis,  and  goniphosis. 

Sutures  are  true  or  false.  In  the  sutura  vera  or  true  suture. 
the  contiguous  margins  are  united  by  a  series  of  interlocking 
processes  and  indentations,  a  thin  fibrous  layer  being  interposed, 
connected  externally  with  the  periosteum.  Variety  of  shape  has 
led  to  the  following  nomenclature  : — sutura  dentata,  where  the 
processes  are  large  and  tooth-like,  as  in  the  interparietal ;  sutura 
serrata,  where  they  are  small  and  fine,  like  the  teeth  of  a  saw, 
as  in  the  interfrontal  ;  and  sutura  limhosa,  where  the  contiguous 
parts  are  dentated  and  also  bevelled,  as  in  the  parieto-occipital — 
the  sutura  lambdoidalis  of  the  human  subject. 

In  the  false  sutures,  or  sutura  notha,  the  bones  are  joined 
by  plain  rough  surfaces,  of  which  there  are  two  forms — sutura 
.squamosa,  where  the  adjacent  borders  are  bevelled,  the  edge  of 
one  bone  resting  on  and  overlapping  the  other,  as  in  the  parieto- 
temporal ;  and  sutura  harmonia,  where  the  articulating  surfaces 
of  two  bones  present  no  marked  irregularity,  as  the  nasal  and 
premaxilla. 

Synchondrosis,  as  already  stated,  resembles  a  suture,  but  the 
connecting  medium  is  cartilage  instead  of  fibrous  tissue  ;  examples 
are  found  in  the  joints  between  the  basi-occipital  and  basi-sphenoid 
bones,  and  between  the  latter  and  the  pre-sphenoid. 

Schindylesis  is  that  form  of  immovable  articulation,  where  a 
ridge  or  .plate  of  one  bone  is  received  into  a  slit  or  fissure  in 
another,  as  the  orbito-sphenoid  into  the  incisura  sphenoidalis  of 
the  frontal  bone. 

Gomphosis  is  the  form  where  one  bone  is  inserted  in  a  cavity 
or  socket  in  another,  as  the  teeth  in  the  alveoli. 


AMPfllARTHROSIS. 


127 


DIARTHHOSIS. 

In  movable  or  true  joints  the  articular  surface  of  each  bone  is 
covered  by  cartilage  of  encrustation ;  the  bones  are  held  together 
"by  ligaments,  the  capsular  one  closing  the  cavity  of  the  joint, 
fvhich  is  lined  by  synovial  membrane.  In  some  joints  there  is 
^  pad  of  fibro-cartilage  interposed  between  the  two  articular 
'Cartilages.  Such  a  pad  is  called  a  meniscus, 
and  it  adds  to  the  elasticity  and  freedom  of  the 
joint.  Movable  joluts  form  the  most  numerous 
ilass;  they  are  found  in  the  limbs  and  else- 
T^^here.  The  chief  varieties  are  the  arthrodia, 
Knarthrosis,  and  the  ginglymus. 

~  In  Arthvodia  the  motion  is  slight  and  glid- 
ing, the  bony  surfaces  being  flat  or  slightly 
undulating,  and  the  motion  limited  by  ligaments 
or  processes  of  bone,  as  in  the  small  bones  of 
the  carpus  and  tarsus.  Enarthrosis,  the  ball- 
-and-socket joint,  is  capable  of  moving  in  any 
<iirection ;  the  extremity  of  one  bone  is  globular, 
and  fits  into  a  cup-shaped  concavity  in  another 
bone ;  the  hip  and  shoulder  joints  are  examples. 
The  Ginglymus,  or  hinge  joint,  although  it  may 
allow  extensive  motion,  limits  it  to  one  plane, 
backwards  and  forwards,  as  in  the  elbow.  A 
Rotatory  joint  (diarthrosis  rotatorius),  where  the 
motion  is  limited  to  rotation,  is  formed  by  a  pivot  on  one  bone 
fitting  into  a  ring  on  another,  as  the  atlo-axoid  joint. 


Fig.  45. 

Diagram  of  a  diar- 
throdial  joint,  a  a, 
Articulating  bones  ; 
c  c  c,  Synovial  mem- 
brane. The  sliaded 
portions  represent 
the  articular  carti- 
lages, which  are  said 
by  some  to  be  covered 
in  early  foetal  life  by 
the  inflected  con- 
tinuations (b  h)  of 
the  synovial  mem- 
brane. 


AMPHIARTHROSIS. 

There  is  but  one  kind  of  amphiarthrosis  or  mixed  joint ;  the 
variations  are  too  slight  to  warrant  separation  into  classes. 

The  term  mixed  is  used  with  reference,  not  to  the  motion 
in  such  joints,  but  to  their  structure,  which  partakes  of  the 
nature  of  both  the  movable  and  immovable,  the  bones  being 
£rmly  joined  together  by  a  strong  interposed  pad  of  fibro- 
cartilage,  which  is  likewise  adherent  to  the  ligaments  of  the 
joint.  There  are  no  capsular  ligaments;  the  cartilaginous 
pad    or    disc   is    softer   towards   the   centre,    where   occasionally 


128  ARTHROLOGY. 

there  may  be  one,  or  even  two,  nan-ow  cavities,  and  authorities 
diflfer  as  to  whether  such  cavities  are  lined  by  synovial  mem- 
brane or  not.  Since  there  are  really  no  frictional  surfaces  in 
such  a  joint,  motion  depends  upon  the  flexibility  of  the  disc. 
The  joints  between  the  vertebral  centra  afford  the  best  illustra- 
tion of  the  mixed  class. 

The  classification  of  the  joints  is  here  tabulated  for  reference. 


Synarthrosis 
(Immovable). 


Sutura. 


( Dentata. 
Yera.  }  Serrata. 
I  Limbosa. 

Notha.  /  Squamosa. 
I  Harmonia. 


Synchondrosis. 
Schindylesis. 
Gom  ptosis. 


Di  arthrosis 
(Movable). 


Arthrodia. 
Enarthrosis. 
Ginglymus. 
Diarthrosis  rotatorius. 


Amphiarthrosis 
(Mixed). 


MOTION    IN   JOINTS. 


The  following-  terms  express  tne  various  movements;  allowed 
by  joints  : — extension  tends  to  bring  two  bones  as  nearly  into  a 
straight  line  as  the  structure  of  the  joint  will  permit ;  flexion  is 
the  reverse  of  this,  and  diminishes  the  angle  that  extension 
increases ;  abduction  expresses  the  outward  movement  of  a  limb 
or  bone  from  the  central  plane  of  the  body ;  adduction  is  the 
reverse  action  ;  rotation  signifies  the  partial  revolution  of  a  bone 
or  number  of  bones,  as  it  were,  on  their  own  axis ;  circumduc- 
tion implies  the  movement  of  the  distal  end  of  a  bone  or  limb, 
when  it  describes  a  curve,  as  the  arc  of  a  circle,  ellipse,  &c.  The 
term  gliding  explains  itself,  and  is  peculiar  to  diarthroses,  other 
joints  having  no  frictional  surfaces. 


common  ligaments.  12^ 

Articulations  of  the  Axial  Skeleton, 
common  vertebral  articulations. 

With  the  exception  of  the  atlas  and  dentata,  which  form 
special  joints,  the  true  YertebroB  present  great  uniformity  in 
their  mode  of  union,  articulating  with  each  other  by  an  amphi- 
arthrosis,  which  unites  their  centra,  and  by  a  pair  of  true  joints 
formed  by  the  oblique  processes.  These  connections  are  com- 
pleted or  strengthened  by  ligaments,  some  of  which  are  comTnon, 
others  special,  the  former  are  continuous,  passing  over  and 
uniting  many  vertebrae,  while  the  latter  exist  separately  between 
the  contiguous  segments. 

The  bodies  are  united  by  intervertebral  discs  of  fibro-cartilage, 
convex  in  front,  and  concave  behind,  firmly  fixed  to  the  articular 
surfaces  of  the  centra.  The  discs  consist  of  laminse  arranged 
concentrically,  with  fibres  crossing  among  themselves,  and  passing 
from  one  articular  surface  to  the  other.  The  central  portion  is 
yellowish,  presenting  more  the  character  of  true  cartilage,  and 
towards  the  circumference  the  laminae  become  denser.  The  discs 
do  not  exist  between  the  first  and  second  cervical  joints ;  they 
are  thick  in  the  neck,  and  thinner  in  the  dorsal  region,  where 
they  assist  in  forming  sockets  for  the  heads  of  the  ribs.  The 
lumbo-sacral  disc  is  very  thick. 

Common   Ligaments. 

These  are  the  Superior  and  Inferior  Common,  and  the  Supra- 
spinous ligaments,  the  latter  in  the  cervical  region  being  termed 
the  Ligamentum  Nuchse. 

The  superior  common  ligament  is  ribbon-like  in  form,  extend- 
ing in  the  spinal  canal  from  the  sacrum  to  the  axis,  placed  upon 
the  superior  part  of  the  bodies  of  the  vertebrae,  to  which,  as  well 
as  to  the  intervertebral  substances,  it  is  attached,  becoming 
broader  at  each  of  the  latter  attachments. 

The  inferior  common  ligament,  situated  below  the  vertebral 
bodies,  stretches  from  the  sacrum  only  to  the  sixth  dorsal 
vertebra,  anterior  to  which  its  place  is  taken  by  a, muscle  called 
the  longus  colli.  It  is  strongest  in  the  posterior  part  of  the 
dorsal  and  in  the  lumbar  regions,  and  broadest  ofi  the  interverte 
bral  substances. 


130  AETHROLOGY. 

Posteriorly  the  supraspinous  ligament  is  a  white  fibrous  cord, 
extending  from  the  spine  of  the  sacrum,  along  the  upper  margin 
of  the  neural  spines  to  the  first  dorsal  vertebrse,  where  its  character 
becomes  so  greatly  changed  that  the  cervical  portion  may  be,  and 
often  is,  described  as  a  separate  structure — the  ligamentum  niichce 
or  ligamentum  colli  (PI.  I.  /  /') ;  it  is  formed  of  yellow  elastic 
tissue,  and  remarkable  for  its  strength,  elasticity,  and  insensibility 
to  pain.  It  consists  of  a  funicular  and  a  lamellar  portion  ;  the 
former,  called  also  the  cord  of  the  ligament,  is  double,  and  extends 
from  the  first,  second,  and  third  dorsal  spines  to  the  occipital 
tuberosity,  continuous  posteriorly  with  the. white  supraspinous 
ligament,  in  which  elastic  tissue  may  be  traced  to  some  distance. 
The  right  and  left  ligaments  meet  in  the  mesian  line,  and  from 
the  postero- inferior  aspect  springs  the  lamellar  portion,  which  is 
flat  and  triangular,  separating  the  muscles  of  the  neck  into  right 
and  left.  It  consists  of  two  plates,  joined  by  cellular  tissue ;  the 
lamellae  or  bands  descending  from  the  cord  and  spinous  processes 
usually  of  the  first  three  dorsal  vertebrae,  run  obliquely  forwards, 
to  be  inserted  to  the  superior  spines  of  the  six  posterior  cervical 
vertebrse,  blending  with  the  interspinous  ligaments.  The  lamellce 
although  widely  separate,  are  connected  by  smaller  branches,  and 
also  by  connective  tissue.  This  ligament  being  highly  elastic,  is 
not  a  binding  ligament,  but  acts  as  a  passive  support  to  the  head 
and  neck,  diminishing  the  muscular  tension  in  the  superior  cervical 
region. 

Special  Ligaments. 

The  special  ligaments  of  a  common  vertebral  articulation  are 
the  interspinous,  the  ligamenta  suhfiava,  the  intertransverse, 
and  the  capsular.  The  interspinous  ligaments  connect  the 
neural  spines,  and  are  continuous  with  the  supraspinous  ligament 
above  ;  they  are  composed  of  yellow  elastic  tissue  in  the  cervical 
region,  elsewhere  of  white  fibrous  tissue.  The  ligamenta  suhfiava, 
or  ligaments  of  the  arches,  connect  the  laminae  of  the  articulating 
vertebrae ;  they  may  be  regarded  as  bifurcations  of  the  inter- 
spinous ligaments,  and  their  regional  structure  varies  like  that  of 
the  latter.  The  intertransverse  ligaments  are  found  between 
the  transverse  processes,  and  are  strongest  in  the  lumbar  region  ; 
these  ligaments  are  well  marked  only  in  the  solipede  (Fig.  60.  a). 
The  capsular  ligaments  invest  the  articulations  of  the  oblique 
processes,  forming  true  synovial  joints. 


SPECIAL    VERTEBRAL    ARTICULATIONS.  131 


SPECIAL  VERTEBRAL  ARTICULATIONS. 

Occipito-atloicl  Articulation. — This  joint  is  formed  by  the 
•occipital  condyles  and  the  glenoid  cavities  of  the  atlas,  and 
possesses  five  ligaments — one  capsular,  two  lateral  or  styloid, 
superior  suspensory,  inferior  suspensory.  This  joint  is  a  true 
one,  having  two  synovial  membranes — one  for  each  condyle.  The 
styloid  ligaments  pass  from  the  base  of  the  occipital  styloid 
processes  to  the  sides  of  the  atlas.  The  superior  suspensory  or 
occipito-atloid  is  very  broad,  and  consists  of  fibres,  which  cross 
each  other,  extending  from  the  superior  margin  of  the  foramen 
magnum  to  the  notch  on  the  anterior  border  of  the  atlas.  The 
inferior  suspensory  or  occij>ito-atloid  stretches  from  a  notch  on 


Fia.  46. 

Neural  canal  of  first  three  cervical  vertebrae,  opened  from  above 
to  show  the  internal  ligaments.  The  occiput  and  foramen  mag- 
num ore  seen  to  the  right.  6,  The  odontoid  ligament ;  a,  The 
occipito-atioid  portion  (long  odontoid) ;  c,  Superior  common 
ligament ;  d,  Posterior  articular  cavity  of  a  vertebral  centrum. 

the  antero-inferior  part  of  the  atlas  to  the  inferior  margin  of  the 
foramen  magnum ;  it  is  thin  and  membranous.  The  capsular 
ligament  passing  completely  round  the  joint,  becomes  blended 
with  the  other  ligaments.  The  latter  are  sometimes  considered 
as  mere  enlargements  or  strengthenings  of  the  capsular  ligament, 
which,  this  view  being  taken,  would  then  become  the  only  liga- 
ment of  the  joint.  This  joint  allows  of  flexion,  extension, 
circumduction,  and  lateral  motion. 

Atlo-axoid  Articulation. — This  joint  is  formed  by  the  oppo- 
sing articular  surfaces  of  the  atlas  and  axis,  and  is  also  a  true 
joint.  The  atlo-axoid  ligaments  are  the  capjsular,  the  superior, 
the  inferior,  and  the  odontoid.  The  capsular  is  very  broad 
superiorly,  where  it  closes  the  atlo-axoid  space.  The  superior 
ligament  passes  from  the  supero-posterior  part  of  the  ring 
of  the  atlas  to  the  neural  spine  of  the  dentata.  The  inferior 
joins  the  inferior  spines  of  the  tM'O  bones.      The  odontoid  springs 


132  ARTHROLOGY. 

from  the  superior  part  of  the  odontoid  process,  inside  the  ring  of 
the  atlas  and  may  be  regarded  as  a  continuation  of  the  superior 
common  ligament ;  it  divides  into  two  strong  bands,  which  become 
attached  on  either  side  to  roughened  surfaces  inside  the  neural 
canal  of  the  atlas.  This  portion  is  sometimes  called  the  short 
odontoid,  while  the  long  odontoid  consists  of  smaller  bands  which 
pass  forwards  and  are  attached  inside  the.  foramen  magnum  of  the 
occipital  bone  ;  the  latter  ligament  is  also  called  the  occipito- 
axoid.  The  motion  of  this  joint  is  purely  rotatory,  being  in  fact 
the  rotatory  joint  of  the  head  ;  or,  in  other  words,  when  the  head 
rotates  the  atlas  moves  with  it.' 

Saca^o-luwhar  Articulation, — This  is  formed  by  the  last 
lumbar  and  first  sacral  vertebrse.  There  are  the  usual  typical 
articulations  between  the  centra  and  zygapophyses,  and  in 
addition  a  pair  of  diarthroses  formed  by  the  facets  on  the  trans- 
verse processes,  which  exist  and  form  joints  also  between  the 
fifth  and  sixth  lumbar  vertebrse  (Fig.  60).  The  usual  vertebral 
ligaments  are  found,  with  the  addition  of  a  pair  of  capsular  ones 
for  the  transverse  joints. 

Coccygeal  Articulations. — These  are  of  the  typical  form,  but 
become  more  and  more  rudimentary  as  the  bones  lose  more  and 
more  the  true  vertebral  character,  the  discs  are  formed,  but  the 
ligaments  become  gradually  blended,  finally  enveloping  the  bones 
in  a  fibrous  sheath. 


Thoracic  Articulations. 

The  thoracic  skeleton  contains  the  articulations  which  unite 
the  dorsal  vertebrae  to  one  another  and  to  the  ribs,  those  which 
connect  the  ribs  and  costal  cartilages,  those  joining  the  latter  to 
the  sternum,  and  finally,  those  which  connect  the  sternal 
segments.     We  have  already  described  the  vertebral  joints. 

Costo-vertehral  Articulation. — A  diarthrodial  connection  is 
here  formed  by  the  head  and  tubercle  of  a  rib,  the  juxtaposed 
facets  on  the  bodies  of  two  dorsal  vertebrse,  and  the  transverse 
process  of  the  posterior  one.  The  ligaments  are  as  follows  : — 
The  stellate  or  radiating  ligament  is  situated  inferiorly,  and 
consists  of  strong  fibres,  divided  into  three  fasciculi,  uniting  the 
head  of  the  rib,  one  to  the  vertebra  in  front,  a  second  to  the 
intervertebral  disc,  while  the  third  passes  to  the  posterior 
vertebra ;  the  interarticular  or  round  ligament  passes  from  the 


THORACIC    ARTICULATIONS, 


133 


ridge  on  the  head  of  one  rib  through  the  articulation,  giving  a 
slip  to  the  intervertebral  disc,  and 
is  attached  to  the  fellow  rib  on  the 
opposite  side ;  the  head  of  the  rib 
is  thus  divided  into  tWo  distinct 
articulations,  with  capsular  liga- 
ments and  synovial  sacs.  Super- 
iorly the  anterior  costo-transverse 
unites  the  neck  of  the  rib  to  the 
infero-anterior  part  of  the  vertebral 
transverse  process,  while  the  p)Os- 
terior  costo-transverse  passes  from 
the  supero-posterior  part  of  the 
tubercle  to  the  lateral  part  of' the 
transverse"  process.  One  capsular 
ligament  unites  the  tubercle  and 
transverse  process,  eoclosing  a  syno- 
vial sac. 


Fig.  47. 

Costo-vertebral  articxilation ,  right  lateral 
aspect,  a,  Anterior,  and  6,  Posterior 
costo-transverse  ligaments  ;  c,  Ligamen- 
tum  subflavum ;  d,  Interspinous,  and 
e,  Supra-spinous  ligaments. 


Costo-vertebral  articulation.  Neural  canal  opened  from 
above,  and  superior  common  ligament  removed,  a.  Inter- 
articular  ligament ;  h  b,  Branches  joining  the  disc. 

Chondro-costal  Articulation. — This  is  a  fixed  joint  between 
the  rib  and  its  cartilage ;  each  rib  is  cupped  on  its  lower 
extremity,  the  convexity  of  the  cartilage  resting  in  it,  and  the 
joint,  a  gomphosis,  is  clothed  around  with  strong  fibrous  tissue. 

Gosto-sternal  Articulation. — This  joint  is  formed  by  two 
sternal  segments  and  a  true  costal  cartilage.  The  first  cartilage, 
however,  articulates  with  the  presternum  only,  and  the  last  only 
with  the  last  sternal  segment.  The  ligaments  are  the  capsular 
and  the  superior  and  inferior  costo-sternal,  which  stretch  from 
the  costal  cartilages  to  the  sternum  above  and  below,  blending 
with  the  capsular  ligament. 

The  asternal  or  false  cartilages  are  united,  each  free  extremity 
becoming  attached  to  the  cartilage  in  front  by  a  small  elastic 
ligament.  The  first  asternal  cartilage  is  very  firmly  attached  to  the 
last  sternal  one ;  a  small  ligament,  the  chondro-xi2')hoid,  is  also 
described,  which  connects  the  xiphoid  and  first  asternal  cartilages. 


134  AETHROLOGY. 

The  first  pair  of  costo-sternal  joints  which  are  close  together 
usually  have  a  common  capsular  ligament. 

Sternal  Articulations. — These  bind  together  the  stiernal  seg- 
ments. The  ligaments  in  the  horse  are  the  superior  sternal, 
extending  along  the  upper  surface  of  the  bones,  and  the  intervening 
fibro-cartilages  which  eventually  ossify. 

The  cartilaginous  appendages  of  the  sternum  are  the  cariniform 
and  xiphoid  cartilages.  In  the  horse  the  former  appears  as  a 
sharp  ridge  running  from  above  aiid  before  the  presternum,  down 
the  lower  mesian  line*  of  the  anterior  sternal  segments.  Its  shape 
bears  a  marked  resemblance  to  the  keel  and  cut- water  of  a  boat, 
hence  its  name.  The  xiphoid  is  a  flat  ovoid  plate  of  cartilage 
attached  to  the  posterior  segment  of  the  meso-sternum ;  unlike 
the  cariniform,  its  sharp  edge  is  placed  transversely.  It  is  also 
called  the  ensiform  cartilage. 


Articulations  of  the  Skull. 

These  are  all  sjniarthrodial,  excepting  the  temporo-maxillary 
joints  aud  those  between  the  hybid  bone  and  its  appendages. 
Collectively,  the  remaining  joints  are  called  the  sutures  of  the 
iikuU,  and  some  of  these  have  received  special  names. 


SUTURES. 

The  straight  median  suture  extending  from  the  occipital  crest 
to  the  nasal  peak  is  the  longitudinal  one,  subdivided  into  the 
nasal  portion,  which  is  open  at  the  apex,  the  frontal,  and  the 
saggital,  the  latter  situated  between  the  parietal  bones,  while 
joining  the  nasal  and  lachrymal  bones  to  the  frontal  is  the  trans- 
verse suture.  The  coronal  suture  extends  obliquely  upwards 
and  backward-s  from  the  temporal  fossa,  between  the  frontal  and 
parietal  bones,  while  the  sutura  limbosa  runs  upwards  between 
the  parietal  and  occipital  bones,  reaching  from  the  temporal  bone 
to  the  saggital  suture.     For  structure  of  sutures  see  page  126. 

TEMPORO-MAXILLARY    JOINT. 

This  articulation  is  a  diarthrosis,  and  it  is  futnished  with 
capsular,  eocternal  lateral,  and  posterior  ligaments,  and  also 
with  a  meniscus  or  interarticular  disc   of  cartilage.     The  joint 


AETICULATIONS    OF    THE    HTOID    SERIES. 


135 


is  formed  by  the  condyle  of  the  inferior  maxilla,  and  the  condyle 
and  glenoid  cavity  of  the  temporal  bone.  The  meniscus  is 
irregular  and  flattened  from  above  downwards,  the  superior 
surface  being  concavo-convex  to  correspond  with  the  condyle  and 
glenoid  cavity  above ;  its 
inferior  surface  being  con- 
cave for  the  reception  of 
the  maxillary  condyle.  The 
capsular  ligament  is  at- 
tached to  the  circumference 
of  the  meniscus,  so  forming 
two  synovial  cavities.  The 
posteriorliga.meiii  runs  from 
the  mastoid  process,  and 
the  external  lateral  one 
from  the  zygomatic  arch  of 
the  temporal  bone,  both 
going  to  the  neck  of  the 
maxilla  ;  both  are  mere  thickenings  of  the  capsular  ligament. 
This  joint  admits  of  lateral  motion,  extension,  flexion,  and  in  the 
herbivora  elevation  and  depression. 


Fig.  49. 
Right  temporo-maxillary  articulation— external  view. 
a,  The  meniscus  ;  b,  External  lateral,  and  c.  Posterior 
ligaments. 


ARTICULATIONS   OF   THE    HYOID    SERIES. 

The   Hyoid   articulations   are    as   follows.      The   temporo- 
hyoid   articulation   is   amphiarthrodial,    the   superior   angle   of 


Fig.  50. 

Hyoid  articulations,    a,  Point  going  to  form  the  tem- 

poro-hyoid  articulation ;    b,  Kudimentary  second  corni- 

culum  ;  c.  Proximal,  and  d,  Distal  interhyoid  articulations. 

the  comu   articulating  with  the  hyoia   process  of  the  petrosal 


136 


ARTHROLOGY. 


bone  by  a  piece  of  fibro-cartilage.  The  'proximal  interhyoid 
articulation  is  also  amphiarthrodial,  a  similar  cartilage  joining  the 
comu  and  corniculum  ;  the  latter  articulates  with  the  hyoid  bone 
by  a  true  synovial  joint,  the  distal  interhyoid. 

In  the  proximal  interhyoid  cartilage  a  small  ossicle  may  be 
found,  which  in  ruminants  appears  as  a  second  corniculum.  The 
motion  in  the  two  first-named  joints  is  considerable.  We  may 
mention  here  that  the  heel  processes  are  attached  at  their  ends 
to  the  thyroid  cartilage  of  the  larynx  by  the  lateral  hyo-thyroid 
ligaments,  between  which  is  found  the  middle  ligament  {see 
*'  Laryngeal  Ligaments  "). 


Articulations  of  the  Appendicular  Skeleton. 

pectoral  limb. 

the  shoulder  joint. 

The  Scapulo-kumeral  articulation  is  formed  by  the  glenoid 
cavity  of  the  scapula,  and  the  articular  head 
of  the  humerus.  It  is  a  baU-and-socket 
joint,  with  one  strong  capsular  ligament 
The  bones  are  held  in  position  by  the  follow- 
ing muscles  which  pass  from  the  shoulder- 
blade  to  the  arm,  and  play  the  part  of 
active  ligaments  : — The  antea  spinatus, 
postea  spinatus,  postea  spinatus  minor,  sub- 
scapularis,  and  flexor  brachii.  The  motion 
^JtHHniHin^  of  the  joint  is  angular,  lateral,  and  circum- 
ductive. 

THE    ELBOW   JOINT. 


The  Humero-radio-ulnar  is  a  ginglymus 
formed  by  the  radius,  ulna,  and  humerus. 
It  has  capsular  and  lateral  ligaments.  The 
capsular  is  strongest  in  front,  where  it 
stretches  from  the  distal  end  of  the  humerus 
to  the  head  of  the  radius ;  posteriorly  it 
encloses  the  articulation  of  the  ulna  with  the 
humerus,  and  it  also  surrounds  the  double 
articulation  between  the  head  of  the  ulna  and 
the  radius.  Anteriorly  it  is  attached  to  the 
tendon  of  the  flexor  brachii,  posteriorly  to  that  of  the  anconeus 


Fig,  51. 

Ligaments   of    the   elbow 

joint  —  posterior   view,     a, 

External   lateral    ligament ; 

b.  Internal  lateral  ligament ; 

c,  External,  and  d.  Internal 
arciform  ligaments. 


SPECIAL    LIGAMENTS. 


137 


Tnuscle.  The  internal  lateral  ligament  is  crucial,  longer  but 
less,  strong  than  the  external ;  it  stretches  from  a  small  tubero- 
sity on  the  inner  side  of  the  internal  condyle  of  the  humerus  to 
the  head  of  the  radius.  The  external  lateral  ligament,  crucial, 
ishort  and  thick,  passes  from  a  ridge  on  the  epitrochlea,  and  a 
cavity  on  its  outside,  to  a  tuberosity  outside  the  h6ad  of  the 
radius.     The  joint  possesses  flexion  and  extension  only. 


RADIO-ULNAR   JOINT. 

This  articulation,  small  and  very  firm,  is 
formed  by  the  articular  surfaces  of  the  radius 
and  ulna,  and  consists  of  two  true  and  two 
mixed  joints.  The  arciform  or  superior  radia- 
ting ligaments  are  attached  on  both  sides  to 
the  superior  part  of  the  ulna  and  radius.  They 
are  curved,  and  blend  with  the  lateral  liga- 
ments of  the  elbow.  Below  the  radio-ulnar 
arch  are  a  few  fibres,  which  constitute  the 
inferior  radiating  ligament.  The  surfaces 
above  and  beneath  the  radio-ulnar  arch  are 
joined  by  the  interosseous  ligaments,  which 
ossify  early  in  life.  The  motion  is  practically 
nil. 

THE  CABPUS. 

The  ligaments  of  this,  joint  or  rather  group 
of  joints,  are  special  and  common.  The 
articulations  between  the  bones  of  the  upper 
row  may  be  termed  the  superior  carpal; 
those  between  the  bones  of  the  lower  row 
the  inferior  carpal ;  between  the  radius  and 
the  upper  row  we  have  the  radio-carjjal ; 
between  the  upper  and  lower  rows  the  hUer-carpal ;  and  between 
the  lower  row  and  the  metacarpus  the  carpo-metacarpal. 


Fig.  62. 

Liijaments  of  the  car- 
pus—anterior aspect,  a, 
Internal  lateral  ligament. 
6,  External  lateral  liga- 
ment; c  c,  Anterior  car- 
pal ligaments  ;  d  d. 
Anterior  carpo-metacar- 
pal  ligaments. 


Special  Ligaments. 

Superior  Carpal  Ligaments. — The  four  bones  of  the  upper  row 
^re  held  together  by  three  anterior  and  three  interosseous 
ligaments.  The  anterior  are  flat  bands  placed  one  between  each 
pair  of   bones ;    and   the   two   inner  ones  are  covered   by  and 


138 


ARTHROLOGY. 


attached  to  the  capsular  ligament ;  the  third,  the  median 
trapezial,  is  covered  by  the  external  lateral  ligament.  The 
interossei  are  attached  to  the  roughened  grooves  between  the 
articular  facets  on  the  lateral  surfaces  of  the  scaphoid,  lunar,  and 
cuneiform  bones.  The  two  inner  are  blended  with  the  anterior, 
while  the  external  one  is  covered  by  the  posterior  common 
ligament. 

Inferior  Carpal. — The  bones  of  the  lower  row  are  held 
together  by  four  ligaments,  two  anterior  and  two  interos- 
seous. The  anterior  are  covered,  the  internal  one  by  the 
internal  lateral,  the  other  by  the  capsular  ligament.  The 
interossei  are  two  ;  the  one  joining  the  mag- 
num to  the  trapezoid  is  blended  with  the 
anterior  ligament,  but  the  other  is  separated 
from  the  corresponding  anterior  one  by  an 
articular  facet, 

Radio-carjoal. — The  special  ligaments  join- 
ing the  radius  to  the  upper  row  are  three  in 
number.  The  oblique  one  stretching  obliquely 
from  the  lower  extremity  of  the  radius,  under 
the  posterior  common  ligament,  to  the  scaphoid 
bone.  A  second  small  one,  the  superior  tra- 
pezial, stretches  from  the  external  side  of  the 
inferior  extremity  of  the  radius  to  the  superior 
border  of  the  trapezium,  partly  covered  by  the 
external  lateral  ligament.  A  third,  the  smallest 
of  all,  is  buried  under  the  former,  and  stretches 
from  the  inferior  part  of  the  radius  to  the  os 
lunare. 

Intercarpal. — There  are  three  special  liga- 
ments ;  two  are  short,  and  situated  under  the 
posterior  common  ligaments.  The  first  runs  vertically  from  the 
scaphoid  to  the  magnum  and  trapezoid,  the  second  passes  obliquely 
from  the  cuneiform  to  the  magnum  ;  while  the  third,  the  inferior 
trapezial,  by  far  the  strongest,  stretches  from  the  trapezium  to  the 
unciform  and  head  of  the  external  splint  bone,  blending  externally 
with  the  lateral,  internally  with  the  posterior  common  ligaments, 
Carpo- metacarpal. — This  joint  has  the  following  special 
ligaments : — two  anterior,  two  posterior,  and  two  interosseous. 
The  first  anterior  consists  of  two  bundles  uniting  the  os 
magnum   to  the  large  metacarpal  bone      The  second  anterior 


Fig.  53. 
Deep  ligaments  of  the 
carpus  —  external  view. 
a  and  6,  Deep  portions 
of  the  external  lateral 
ligament ,  c,  Superior,  d, 
Median  and  e.  Inferior 
trapezial  ligaments. 


COMMON    CAPPAL    LIGAMENTS. 


139 


binds  the  unciform  to  the  extemal  splint  bone  The  two 
posterior  bind  the  magnum  and  trapezoid  to  the  large  and 
inner  metacarpal  bones.  The  interossei  unite  the  heads  of 
the  splint  bones  to  the  large  metacarpal  and  bones  of  the  lower 
row. 

Common  Ligaments. 

The  Common  Ligaments  are  the  external  and  internal  lateral^ 
and  the  anterior  and  ^posterior  common,  or  capsular. 

The  internal  lateral  ligament,  stronger 
than  the  external  one,  is  slightly  crucial, 
consisting  of  two  bundles  of  fibres  which 
cross  each  other;  both  spring  from  the 
internal  side  of  the  inferior  extremity  of 
the  radius ;  the  superficial  bundle  goes 
to  the  OS  magnum  and  large  metacarpal, 
and  the  deep  set  to  the  scaphoid,  trape- 
zoid, and  inner  splint  bones.  A  part  of 
this  ligament,  deep-seated  also,  joins  the 
scaphoid  and  small  metacarpal  bones. 

The  external  lateral  ligament  also  con- 
sists of  two  fasciculi,  springing  from  the 
external  side  of  the  distal  end  of  the 
radius ;  the  superficial  fibres  are  attached 
to  the  external  splint,  the  deep  to  the 
same,  and  also  to  the  cuneiform  and 
unciform  bones. 

The  anterior  common  or  capsular 
ligament  is  membranous,  covering  the 
anterior  portion  of  the  carpus.  This 
ligament  is  attached  to  the  radius,  the 
head  of  the  large  metacarpal  bone,'  the 
lateral  ligaments,  and  to  the  carpal 
bones  and  their  anterior  ligaments. 
The  annular  ligaments  are  thickenings  of  this  structure, 
which  bind  down  the  extensor  tendons.  The  inner  surface 
is  smooth,  and  lined  by  synovial  membrane.  The  posterior 
common  ligament  is  one  of  the  strongest  in  the  body,  and 
covers  the  posterior  surface  of  the  carpus,  filling  up  the  depres- 
sions. It  passes  from  the  distal  end  of  the  radius  to  the  head  of 
the  large  metacarpal  bone,  adhering  to  the  internal  lateral,  median. 


Fig.  54. 
Ligaments  of  the  carpus  — 
postero-lntemal  view,  a  6,  Deep 
portions  of  internal  lateral  liga- 
ment ;  c,  Obliqae  ligament ;  d. 
Interosseous  metacarpal  liga- 
ment; e.  External  Interosseous 
ligament  of  the  upper  row. 


140 


ARTHROLOGY. 


and  inferior  trapezial  ligaments.  Its  anterior  surface  is  attached 
to  the  two  rows  of  bones,  while  its  posterior  is  smooth,  for  the 
passage  of  the  great  flexor  tendons ;  the  inferior  carpal  or  cheek 
ligament  is  continuous  with  it.  A  ligamentous 
structure  passes  obliquely  downwards  from  the 
posterior  border  of  the  trapezium  to  the  large 
and  inner  metacarpal  bones,  completing  the 
carpal  groove  or  sheath  for  the  flexor  tendons; 
this  is  the  posterior  or  investing  annular  liga- 
ment. The  carpal  or  check  ligaments,  superior 
and  inferior,  will  be  alluded  to  in  describing 
the  muscles  of  this  region. 

The  synovial  capsules  are  four,  perhaps 
Jive — two  small  and  three  large.  Of  the 
latter,  one  is  for  the  radius  and  the  upper  row, 
extending  between  the  bones  as  far  as  the 
interossei;  another  is  situated  between  the 
upper  and  lower  rows,  and  a  third  between 
the  lower  row  and  metacarpus,  dipping  be- 
tween its  large  and  small  bones.  There  is 
usually  a  separate  synovial  capsule  between 
the  trapezium  and  cuneiform  "bone,  and  perhaps 
one  foj  the  pisiform,  when  present. 

Motion  in  the  carpus  takes  place  chiefly 
in  the  radio-carpal  portion,  to  a  far  less  degree 
in  the  intercarpal,  and  very  slightly  in  the 
carpo-metacarpal ;  the  movements  are  flexion  and  extension  ;  very 
slight  lateral  and  circumductive  movements  are  possible. 


Fig.  65. 
Superficial  ligaments 
of  the  carpus— posterior 
view,  a.  Posterior  annu- 
lar ligament ;  6  b.  Pos- 
terior common  ligament. 


METAC-\RPAL    ARTICULATION. 

This  consists  of  diarthrodial  and  synarthrodial  joints.  The 
latter  are  furnished  with  interosseous  ligaments,  which  very 
generally  become  ossified ;  the  articular  surfaces  of  the  former 
are  held  together  partly  by  those  carpal  ligaments  which  sur- 
round them,  and  partly  by  the  interosseous  ligaments  just 
named. 


METACARPO-PHALANGEAL    ARTICULATION. 

This,  whi'^h  is   popularly  termed  the  fetlock  joint,  is  formed 
by  the  large  metacarpal  bone,  the  proximal  phalanx,  and  a  pair 


METACARPO-PHALANGEAL    ARTICULATION. 


141 


jbf  sesamoids.  The  ligaments  may  be  divided  into  those  proper 
to  the  joint  and  the  accessory.  The  former  consist  of  a  capsular 
and  two  lateral  ones.  The  capsular  ligament  passes  from  the 
lower  end  of  the  large  metacarpal  bone  to  the  head  of  the  os 
suffraginis,  and  is  attached  to  the  lateral  liga- 
ments, which  stretch  from  the  infero-lateral 
aspect  of  the  metacarpus  to  the  supero-lateral 
surface  of  the  os  suffraginis. 

The  accessory  ligaments  are  those  imme- 
diately connected  with  the  sesamoid  bones. 

The  superior  sesamoidean  or  suspensory 
ligament  is  a  long,  strong  band, 
arising  posteriorly  from  the  lower 
bones  of  the  carpus  and  the  head 
of  the  metacarpus,  occupying  the 
space  between  the  splints.  It 
bifurcates,  and  becomes  attached 
to  the  summits  of  the  sesamoids, 
whence  the  parts  pass  downwards 
and  forwards,  reuniting  as  the 
broad  ligament,  and  joining  the 
extensor  pedis  tendon  at  the 
antero-inferior  part  of  the  os 
suffraginis. 

Th^inferior  sesamoidean  liga- 
ments are  named  the  external  or 
long,  the  middle  or  short,  and 
the  internal  or  crucial.  The 
external  one  is  Y-shaped,  and 
runs  from  the  base  of  the  sesamoids  to  the 
supero-posterior  part  of  the  os  coronae.  The 
middle  one  is  V-shaped,  arising  from  the  base 
of  the  sesamoids,  and  it  passes  down  to  a 
ridge  on  the  back  of  the  os  suffraginis.  The 
internal  one,  crucial  or  X-shaped,  likewise 
passes  from  the  base  of  the  sesamoids  to  the 
supero-posterior  part  of  the  os  suffraginis,  its  fibres  intercrossinp. 
The  lateral  sesamoidean  ligaments,  external  and  internal,  are 
two  thin  layers,  passing  from  the  external  surfaces  of  the  sesa- 
moids to  the  tubercles  on  the  head  of  the  os  suffraginis.  Pos- 
teriorly, the  sesamoid  bones  are  connected  by  the  interosseous 


Fig.  56. 
Sesamoidean  and  digi- 
tal ligaments— posterior 
aspect,  a,  Suspensory 
ligament;  6  6  6,  External 
and  middle  inferior  sesa- 
moidean ligaments.  The 
central  bundle  is  the  Y, 
the  two  lateral  ones 
forming  the  V  ligament; 
c,  Annular  sesamoidean 
ligament;  dd,  Posterior 
ligaments  of  the  pastern 
joint ;  e  e.  Lateral,  and 
/,  Inferior,  navicular 
ligaments. 


Fig.  57. 
Deep  sesamoid, 
ean  ligaments,  a, 
Inter-sesamoidean 
ligament ;  6,  Cru- 
cial or  X  liga- 
ment. 


142  ARTEROLOGT. 

or  intersesamoidean  ligament,  and  covered  by  a  pad  of  fibro- 
cartilage,  which  forms  a  smooth  groove  for  the  passage  of  the 
flexor  tendons,  and  is  converted  into  a  canal  by  the  annular 
ligament,  a  strong  fibrous  band  which  forms  an  arch  posteriorly 
from  one  sesamoid  bone  to  the  other.  The  joint  is  capable  of 
flexion  and  extension,  with  very  slight  lateral  motion. 

The  synovial  membrane  of  this  joint  is  continued  upwards 
posteriorly,  in  the  bifurcation  of  the  suspensory  ligament,  where 
it  forms  a  large  cul-de-sac.  "  Wind-galls "  are  projections  of 
this  sac  when  it  is  abnormally  full. 


PASTERN    JOINT. 

The  Proximcd  interphalangeal  articulation,  or  pastern  joint, 
is  formed  by  the  proximal  and  mesian  phalanges,  joined  by  the 
capsulai',  lateral,  and  two  posterior  ligaments.  The  capsular 
ligament  extends  from  the  articular  margin  of  one  bone  to  that 
of  the  other,  and  is  adherent  in  front  to  the  extensor  tendon. 
The  lateral  ligaments  are  large  and  very  strong,  springing  from 
the  distal  end  of  the  os  suffraginis  and  passing  obliquely 
downwards  to  the  postero-lateral  aspect  of  the  os  coronse. 
The  two  posterior  ligaments  run  each  from  three  points 
on  the  sides  of  the  os  suffraginis  to  a  piece  of  fibro-cartilage, 
described  as  the  glenoid  cartilage,  and  attached  to  the  postero- 
superior  edge  of  the  os  coronae  ;  between  them  is  the  insertion 
of  the  external  inferior  sesamoidean  or  Y-shaped  ligament. 

The  synovial  membrane  of  this  joint  lines  the  glenoid  cartilage 
and  a  portion  of  the  extensor  tendon,  and  sends  upwards  a  sac 
which  lies  between  the  postero-inferior  part  of  the  first  phalanx 
and  the  cartilage.  The  movements  are  flexion  and  extension, 
and,  durinof  flexion,  some  slight  lateral  motion. 


COFFIN    JOINT. 

The  Distal  interphalangeal  articulation,  or  coflSn  joint,  is 
formed  by  the  mesian  and  distal  phalanges  and  the  navicular 
bone.  Its  ligaments  are  the  capsular,  antero  and  ]postero- 
lateral,  and  the  broad,  lateral,  and  inferior  navicular.  The 
capsular  ligament  includes  the  articulation  formed  by  the  three 
bones,  and  is  attached  to  the  extensor  tendon  in  front  and  the 
flexor  behind.      The  antero-lateral,  which  are  strong  and  thick. 


THE    PELVIS. 


143 


spring  from  the  imprints  on  the  lateral  aspect  of  the  os  coronae, 
and  are  inserted  into  two  depressions  at  the  superior  border  of 
the  OS  pedis,  partly  covered  by  the  lateral  cartilages. 

The  postero-lateral  are  continuations  of  the 
lateral  ligaments  of  the  pastern  joint,  which, 
after  reaching  the  os  coronse,  form  an  elastic 
iibrous  cord,  attached  to  the  upper  border  of 
the  navicular  bone,  the  two  uniting  to  form 
the  superior  or  hroad  ligament  They  give 
off  short  lateral  bundles  to  the  retrossal  pro- 
cesses and  inner  surfaces  of  the  lateral  carti- 
lages. The  lateral  navicular  ligaments  con- 
sist of  strong  white  fibres,  which  join  the  angles 
of  the  navicular  bone  to  the  inner  aspect  of 
the  lateral  cartilages,  and  the  wings  of  the  os 
pedis.  The  inferior  ligament  is  an  inter- 
osseous one,  which  is  attached  to  a  roughened 
groove  on  the  anterior  border  of  the  navicular 
bone  and  to  the  semilunar  ridge  of  the  os 
pedis.  The  synovial  taemhrane  lines  the 
cavity  of  the  joint,  and  sends  upwards  a  very 
large  sac  along  the  posterior  surface  of  the 
median  phalanx.  Smaller  projections  are  found  between  the 
anterior  and  posterior  lateral  ligaments.  The  motion  of  the  joint 
is  that  of  flexion  and  extension. 


Fig.  58. 
Navicular    ligaments. 
a  a,  Superior,  or  broad ; 
b.  Inferior  ;  andc  c,  Late- 
ral ligaments. 


Articuiations  of  the  Pelvic  Limb, 
the  pelvis. 

Bacro-iliac  Articulation. — This  is  the  articular  connection 
hetween  the  axial  skeleton  and  the  pelvic  limb  ;  it  is  described 
both  as  a  diarthrosis  and  an  amphiarthrosis  ;  it  is  capable  of  little 
motion,  and  the  synovia  is  small  in  quantity,  if  present  at  all ;  the 
joint  is  formed  by  the  venter  of  the  ilium,  and  the  supero-lateral 
surface  of  the  sacrum,  which  articular  surfaces  are  clothed  with 
cartilage,  and  the  union  completed  by  the  three  sacro-iUac  liga- 
ments, inferior,  lateral  and  superior.  The  inferior  consists  of 
strong  .jundles  of  fibres,  which  envelop  the  articulation  like  a 
strong  and  irregular  capsular  ligament,  and  are  attached  below  to 
the  transverse  process  of  the  sacrum,  and  above  to  the  venter 
ilii.      The  superior  sacro-iliac,  short  and  strong,  stretches  from 


144  ARTHROLOGY. 


the  spines  of  the  sacrum  to  the  posterior  spine  of  the  ilium.     The 
lateral    sacro-iliac  is   triangular,  the   fibres    running    obliqueljr 


Fig.  59. 
Sacral  and  peMc  ligaments— left  lateral  aspect,     a,  Superior  sacro-iliac  liga- 
ment ;   h,  Sacral   ligament ;    c,  Lateral   sacra-iliac   ligament ;    d,  Sacro-sciatic 
ligament. 

backwards,  and  it  is  attached  above  to  the  posterior  spine  and 
border  of  the  ilium,  below  to  the  lateral  border  of  the  sacrum. 
Sacro-sciatic  Ligament — This  is  a  broad  membranous  expan- 


Fia.  60. 

Sacral  and  pelvic  ligaments— inferior  aspect,  a.  Intertransverse 
lumbar  ligament ;  b  and  c.  Capsular  ligaments  of  lumbar  and  sacro- 
lumbar  transverse  articulations  ;  d,  Inferior  sacro-iliac  ligament ;  e. 
Obturator  ligament ;  //,  Ligament  of  the  ischio-pubic  symphysis. 

sion  situated  at  the  side  of  the  pelvis,  helping  to  form  the  pelvic 
cavity.  It  is  attached  superiorly  to  the  lateral  borders  of  the 
transverse  processes  of  the  sacrum  and  first  two  or  three  coccygeal 


HIP    JOINT.  145 

vertebrae  ;  inferiorly,  to  the  superior  ischiatic  spine  and  tuberosity 
of  the  ischium.  Between  this  ligament  and  the  iliac  shaft  is  a 
space,  the  great  sciatic  notch  ;  and  a  second,  the  lesser  sciatic 
notch,  exists  between  the  ligament  and  the  ischial  shaft.  The 
former  gives  passage  to  the  great  sciatic  nerve  and  gluteal  blood- 
vessels, the  latter  to  the  tendons  of  the  obturator  internus  and 
pyriformis  muscles. 

Some  lateral  bands  are  found  joining  the  sacral  spines  to  the 
transverse  processes ;    these  are  termed  the  sacral  ligaments. 

Pelvic  or  Ischio-puhlc  Symphysis. — This  articulation  is  formed 
by  the  respective  surfaces  of  the  ischium  and  pubis,  and  joins  the 
right  and  left  ossa  innominata  ;  in  the  young  it  consists  of  fibro- 
cartilage  and  white  fibrous  tissue,  which  ossify  with  age. 

The  Obturator  ligam,ents  are  thin  membranes,  almost  closing 
up  the  obturator  foramina,  a  small  passage  being  left  for  the 
transit  of  blood-vessels. 

HIP   JOINT. 

The  Femoro-pelvic  is  a  ball-and-socket  or  enarthrodial  joint, 
and  is  formed  by  the  acetabulum  of  the  os  innominatum  and  the 
e-rticular  head  of  the  femur.      It  has  the  following  ligaments  : — 


Ligaments  of  thehip  joiDt — infero-internalview. 
a,  Cotyloid  ligament ;  b,  Round  ligament;  c,  Pubio- 
femoral,  crossed  by  the  transverse  ligament. 

The  capsular,  which  grasps  the  brim  of  the  acetabulum  and 
roughened  edge  of  the  head  of  the  femur  ;  the  cotyloid,  which 
surrounds  and  deepens  the  acetabulum ;  and  the  transverse, 
which  stretches  over  the  cotyloid  notch,  completing  the  circum- 

L 


146 


ARTHROLOGY. 


ference  of  the  cavity,  but  leaving  a  space  for  the  passage  of  the 
pubio-feinoral  ligament. 

The  binding  ligaments  of  the  joint  are  two — the  round  or 
ligamentum  teres,  very  short  and  strong,  which  arises  from  the 
notch  in  the  head  of  the  femur,  and  is  inserted  in  the  fundus 
acetabuli;  the  second  is  the  pubio-femeral  ligament,  which 
arises  from  the  head  of  the  femur,  close  by  the  round  ligament ; 
bound  down  by  the  transverse  ligament,  it  passes  through  the 
cotyloid  notch  and  along  the  groove  on  the  under  side  of  the 
pubis,  meeting  and  crossing  its  fellow 
at  the  symphysis,  and  becoming  con- 
tinuous with  the  abdominal  fascia  of 
the  opposite  side ;  thus  the  head  of 
the  right  femur  is  partially  supported 
in  position  by  the  muscles  of  the  left 
side,  and  vice  versa.  As  it  passes  over 
the  pubis,  a  synovial  bursa  is  inter- 
posed. This  ligament  is  peculiar  to 
the  Equidse.  The  motion  of  the  joint 
is  flexion,  extension,  abduction,  adduc- 
tion, rotation,  and  circumduction. 

STIFLE  JOINT. 


Fig.  62. 

Ligaments  of  the  stifle  joint  — 
antero-internal  aspect,  a.  Internal 
lateral  femoro-tibial  ligament ;  h,  In- 
ternal lateral  patellar  ligament;  c, 
Internal,  d,  Middle,  and  «,  External 
straight  patellar  ligaments. 


The  Femoro-tibial  articulation,  a 
compound  ginglymus,  is  formed  by  the 
trochlea  and  condyles  of  the  femur,  the 
tibia,  and  patella.  The  ligaments  con- 
sist of  two  groups,  the  femoro-tibial 
and  the  patellar. 

Patellar  Group. — The  capsular 
ligament,  which  is  attached  round  the  trochlea  of  the  femur,  and  thp 
articular  surface  of  the  patella,  is  capacious,  alloAving  considerable 
motion  in  the  joint.  The  lateral  ligaments,  internal  and  external, 
arise  from  the  lateral  aspects  of  the  femur,  just  above  the  condyles, 
and  are  inserted  to  the  corresponding  surfaces  of  the  patella,  the  ex- 
ternal being  the  larger;  they  may  be  regarded  as  thickened  portions 
of  the  capsular  ligament.  The  three  straight  ligaments,  external, 
middle,  and  internal,  arise  from  the  antero-inferior  surface  of 
the  patella,  and  are  inserted  to  the  anterior  aspect  of  the 
tuberosity  of  the  tibia,  the  middle  one  occupying  the  small  fossa. 


STIFLE    JOINT. 


147 


At  its  patellar  attachment,  the  internal  straight  ligament  becomes 
enlarged,  and  fibro-cartilaginous  in  structure,  projecting  over  the 
edge  of  the  femoral  trochlea,  and  thus  enlarging  the  articular 
surface  of  the  patella. 

Femoro-tlhlal  Group. — There  are  two  crescentic  fibro-carti- 
lagiuous  discs,  the  semilunar  cartilages  or 
"menisci,  interposed  between  the  condyles  of 
the  femur  and  the  head  of  the  tibia,  the 
internal  one  being  the  larger  and  thinner. 
Their  internal  borders  are  sharp  and  con- 
cave, embracing  the  tibial  sjDine,  while  the 
external  are  thick  and  convex.  Their  super- 
ior surfaces  are  hollowed  for  the  reception 
of  the  femoral  condyles,  while  the  inferior 
are  smooth  and  fiat,  resting  on  the  tibia. 
Their  extremities  terminate  in  the  coronary 
ligaments,  which  attach  them  to  the  bones; 
these  Sixe  five  in  number,  two  for  the  inter- 
nal disc,  an  anterior  one  attaching  it  to  an 
excavation  in  front  of,  while  the  posterior 
one  is  fixed  to  a  furrow  behind,  the  tibial 
spine.  The  external  disc  has  three,  one 
fixed  in  front  of  the  tibial  spine,  and  two 
behind  it,  of  which  the  superior  one  is 
longer  and  stronger,  being  inserted  in  the 
intercondyloid  notch  of  the  femur,  while  the 
inferior  is  thin  and  flat,  and  fixed  to  the 
head  of  the  tibia. 

Crucial  or  Iiderosseus  Ligaments. — 
These,  anterior  and  posterior,  are  very 
strong,  and  are  situated  between  the  con- 
dyles of  the  femur.  The  anterior  or  exter- 
nal stretches  obliquely  forwards,  and  is 
attached  in  the  intercondyloid  notch  inside 
the  external  condyle  of  the  femur,  and  to 
a  depression  on  the  summit  of  the  tibial 
spine.  The  posterior  or  internal,  the  longer,  arising  anteriorly 
inside  the  internal  condyle,  crosses  the  anterior  ligament,  and  is 
attached  posteriorly  to  a  small  eminence  behind  the  inner  articu- 
lar surface  of  the  head  of  the  tibia. 

Lateral  Ligaments. — The  external  one,  the  shorter  and  stronger 


Fio.  63. 
Ligaments  of  the  stifle  joint 
— posterior  aspect,  a.  Exter- 
nal lateral  patellar  ligament ; 
6,  External  lateral  femoro- 
tibial  ligament ;  c,  Posterior 
crucial  ligament ;  d,  External 
meniscus  ;  e,  Internal  menis- 
cus ;  f,  Femoral  coronary  liga- 
ment ;  g,  Posterior  external 
coronary  ligament ;  \  Fibulo- 
tibial  ligament. 


148  ARTHROLOGY. 

arises  from  the  external  condyle  of  the  femur,  and.  passes  over 
the  head  of  the  tibia  to  the  fibula ;  a  synovial  bursa  lies  between 
it  and  the  tibia.  It  is  separated  from  the  capsular  ligament  by 
the  tendon  of  origin  of  the  popliteus.  The  internal  lateral  arises 
from  the  internal  condyle  of  the  femur,  and  is  attached  to  the 
intero-lateral  aspect  of  the  head  of  the  tibia. 

Capsular  Ligament. — This  name  is  usually  applied  to  a  mem- 
branous ligament  enclosing  the  joint  posteriorly,  and  attached  to 
the  femur,  tibia,  lateral  ligaments,  and  menisci.  It  is  by  some 
called  tho  posterior  ligament.  Anterior  to  this  there  is  a  pair 
of  membranes  enclosing  the  joint  antero-laterally.  These  are 
generally  described  as  the  synovial  membranes;  bat  as  they  are 
considerably  strengthened,  and  help  to  play  the  part  of  a  capsular 
ligament,  it  may  be  convenient  to  describe  them  as  such.  There 
is  therefore  a  complete  capsular  ligament  investing  the  joint, 
thickened  posteriorly. 

The  synovial  apparatus  is  double,  each  side  having  its  own 
membrane,  and  between  the  two  are  the  crucial  ligaments  of 
the  joint.  Anteriorly,  the  synovial  membranes  contact  that  of  the 
femoro-patellar  joint,  and  it  is  found  that  sometimes  the 
synovial  cavities  are  continuous  with  that  of  the  latter.  A  large 
quantity  of  fat  fills  up  the  space  between  the  capsules  and  the 
straight  ligaments  of  the  patella.  The  motions  of  this  joint  are 
flexion  and  extension,  and  a  certain  amount  of  rotation,, 
permitted  by  the  presence  of  the  disss. 


TIBIO-FIBULAR    ARTICULATION. 

This  small  articulation  is  formed  by  the  facets  on  the  adjacent 
surfaces  of  the  tibia  and  fibula,  and  is  a  diarthrodial  joint.  The 
ligaments  are  a  strong  capsular  one  and  the  interossei,  which 
divide  into  superior  and  Inferior ;  the  former  being  a  small 
bundle  at  the  upper  third  of  the  fibula ;  the  latter  consists  of  a 
membranous  expansion,  extending  from  the  middle  to  the  distal 
extremity  of  the  fibula.  Between  the  two  interosseous  parts 
pass  the  chief  artery  and  vein  of  the  region,  the  anterior  tibial. 
A  ligamentous  cord  extends  downwards  from  the  fibula  to  the 
external  malleolus  of  the  tibia,  "  where  this  cord  bifurcates  and 
unites  with  the  two  external  lateral  ligaments  of  the  tarsal  joint'' 
CRigot).     Motion  in  this  joint  can  hardly  be  said  to  exist. 


COMMON    LIGAMENTS. 


149^ 


THE    TARSUS. 


Similar  to  the  carpus,  this,  the  hock  joint,  consists  of  a  true  or 
tihio-tarsal  portion,  together  with  the  upper  arid  lower  tarsal^ 
the  intertarsal,  and  the  tarso-metatarsal  accessory  articulations- 
The  ligaments  are  common  and  special. 


Common  Ligaments. 

These  are  the  external  and  internal  lateral  and  the  capsular^ 
The  internoX  lateral  is  formed  of  three 
fasciculi  of  fibres,  superficial,  middle,  and 
deep.  The  superficial,  the  longest  and 
strongest,  connects  the  internal  malleolus 
of  the  tibia  with  the  astragalus,  two 
cuneiform,  and  the  large  and  inner  meta- 
tarsal bones.  The  middle  fasciculus,  con- 
sisting of  two  cords,  likewise  arises  from 
the  internal  malleolus  of  the  tibia,  one 
division  being  attached  to  the  astragalus, 
the  other  to  the  calcaneum.  The  deep 
fasciculus  is  very  small;  it  passes  from 
the  internal  malleolus  to  the  astragalus. 
The  external  lateral  ligament  consists  of 
two  crucial  fasciculi,  superficial  and  deep. 
The  superficial  is  strong  and  flat,  joining 
the  external  malleolus  of  the  tibia  to  the 
astragalus,  calcaneum,  cuboid,  large  and 
external  metatarsal  bone..  The  deep 
fasiculus  is  short ;  it  passes  obliquely 
backwards,  arising  from  the  external 
malleolus  of  the  tibia,  to  the  astragalus 
and  calcaneum.  The  capsular  ligament  is  very  strong,  and 
attached  superiorly  round  the  distal  articular  surface  of  the  tibia, 
to  the  inferior  border  of  the  astragalus,  to  the  cuneiforme  mag- 
num and  medium,  and  to  the  lateral  and  oblique  ligaments  ; 
posteriorly  it  is  attached  to  .the  calcaneum  and  astragalus,  and 
there  is  a  fibro-cartilaginous  disc  in  its  centre,  over  which  glides, 
the  flexor  tendon,  furnished  with  a  synovial  membrane. 

The  capsular  ligament  is  often  described  as  double,  and  named' 
the  anterior  and  posterior,  the  lateral  ligaments  with  which  it. 
blends  being  the  lines' of  division. 


Fio.  64. 
Ligaments  -of  the  tarsus— pos- 
tero-internal  view,     a,   Internal 
Jateral   ligameuL;    6,    Calcaneo- 
cuboid ligament. 


150 


ARTHROLOGY. 


Special  Ligaments. 

Superior  Tarsal. — These  ligaments  occur  between  the  astra- 
galus and  calcaneum,  and  consist  of  one  superior,  two  lateral, 
and  one  interosseous.  The  superior  stretches  from  the  upper 
border  of  the  pulley  of  tlie  astragalus  to  the  calcaneum;  the 
lateral  are  very  thin,  and  covered  by  the  lateral  common  liga- 
ments ;  the  interosseous  one  is  strong,  occupying  the  greater 
part  of  the  rough  excavation  between  the 
articular  facets  of  the  bones. 

Inferior  Tarsal. — The  ligaments  of  the 
lower  row  are  five,  tiuo  anterior,  which  con- 
nect the  cuboid  to  the  great  and  middle 
cuneiform  bones,  and  three  interosseous 
ones,  two  of  v/hich  correspond  to  the  anterior 
ligaments  ;  the  third  interosseous  ligament 
unites  the  three  cuneiform  bones.  Some  of 
these  ligaments  bound  the  tarsal  foramen, 
which  gives  passage  to  the  perforating  pedal 
artery. 

Intertarsal. — The  four  ligaments  in  this 
group  are  of  greater  importance  than  those 
of  the  two  last  groups.  The  calcaneo-cuboid 
or  calcaneo-metatarsal  ligament  stretches 
from  the  posterior  border  of  the  calcaneum 
to  the  posterior  part  of  the  cuboid,  termina- 
ting on  the  head  of  the  external  metatarsal 
bone  ;  externally  it  reaches  the  lateral,  in- 
ternally the  tarso- metatarsal  ligament.  This 
ligament  becomes  implicated  in  the  lesion 
known  as  curb. 

The  Oblique,  or  A  stragalo-metatarsal  ligament,  arising  from 
the  antero-internal  side  of  the  astragalus,  becomes  attached  to 
the  cuneiforme  magnum  and  medium,  the  large  metatarsal  bone, 
and  the  capsular  ligament,  the  fibres  radiating  from  above,  and 
running  downwards  and  outwards.  This  ligament  covers  the 
seat  of  bone-spavin. 

The  Tarso-metatarsal  is  a  single  strong  ligament,  which 
covers  the  tarsal  groove  and  unites  posteriorly  all  the  bones  of 
the  joint  to  the  three  metatarsal  bones.  It  is  smooth,  for  the 
passage  of  the  flexor  tendon,  and  is  the  analogue  of  the  posterior 


Fio.  65. 
Ligaments  of  the  tarsus 
anterior-external    view,      i 
External     lateral,      and 
Oblique  ligament. 


RUMINANTIA AXIAL    SKELETON.  151 

carpal  ligament.  It  is  pierced  by  the  perforating  pedal  artery 
and  vein,  and  inferiorly  may  be  continuous  with  the  check 
ligament.  The  great  interosseous  ligar)ient  unites  the  calcaneum 
and  astragalus  to  the  cuboid  and  cuneiforme  magnum,  occupying 
the  internal  space  formed  by  these  bones. 

Annular  Ligaments. — The  posterior  of  these  closes  in  the 
tarsal  groove,  completing  the  sheath  for  the  deep  flexor  tendon  ; 
hence  it  passes  from  the  tuberosity  and  posterior  border  of  the 
calcaneum  to  the  internal  ridge  of  the  same  bone,  and  is  reflected 
as  far  down  as  the  inner  metatarsal  bone.  It  is  strengthened 
by  a  strong  band  which  arises  almost  with  the  calcaneo- cuboid 
ligament.  The  anterior  annular  ligament  presents  three  well- 
marked  portions  ;  they  are  strong  and  more  or  less  flattened 
bands,  an  inferior  one  passing  across  from  the  proximal  end  of  the 
outer  to  that  of  the  inner  metatarsal  bone,  a  middle  one  attached 
to  the  cuboid  bone  and  flexor  metatarsi  tendon,  and  a  superior 
crossing  the  distal  end  of  the  tibia  obliquely  outwards  and  down- 
wards. The  three  portions  of  this  ligament  bind  down  the 
terdons  playing  over  the  tarsus  anteriorly. 

There  are  at  least  three  synovial  membranes,  one  between  the 
astragalus  and  tibia,  another  between  the  rows  of  bones,  and  one 
also  between  the  lower  row  and  the  metatarsus,  which  sends  a 
branch  upwards  between  the  calcaneum  and  astragalus. 

The  motion  in  the  tarsal  joint  is  in  effect  limited  to  flexion 
and  extension,  and  the  joint  may  therefore  be  regarded  as  a 
ginglymus. 

The  tarsal  check  ligament  will  be  described  with  the  muscles. 
The  metatarsal,  metatarso-phalangeal,  and  interphalangeal  joints. 
are  like  those  of  the  anterior  limb. 


COMPAEATIVE  ARTHROLOGT. 

RUMINANTIA. 

AIIAL  SKELETON. 

In  the  ox,  the  dorso-liunhar  supraspinous  ligameut  is  composed  of  yellow 
elastic  tissue,  and  anteriorly  is  expanded,  and  attached  to  the  sides  rather  than 
to  the  summits  of  the  neural  spines.  The  inferior  common  ligament  is  very 
strong,  and  the  intervertebral  discs  thicker  than  those  of  the  horse ;  the  ligamen- 
turn  nuchcE  is  also  stronger,  as  the  weight  it  has  to  bear  is  greater.  The  sternal 
ribs  articulate  with  their  cartilages  by  means  of  true  diarthroses,  and  are 
supplied  with  synovial  membranes.  The  sternum  is  furnished  with  an  inferior 
common  ligament,  and  the  presternum  or  manubrium  articulates  with  the  meso- 


152  COMPAEATIVE  ARTHKOLOGY. 

sternum  by  a  diarthrosis  of  limited  motion.     The  transverse  lumbo-sacral  and 
interlumbar  axticulations,  being  peculiar  to  tbe  horse,  are  entirely  wanting  here. 

PECTORAL   LIMB. 

In  the  elbow  joint  the  internal  lateral  ligament  is  shorter  than  the  external. 
The  carpus,  being  articulated  on  the  same  general  plan  as  that  of  the  horse,  calls 
for  no  special  description.  The  metacarpo -phalangeal  joint  is  double,  each  digit 
articulating  in  a  manner  very  like  the  single  one  of  the  horse,  and^each  having 
two  lateral  ligaments.  The  s^ispensory  ligament  divides  into  several  parts 
inferiorly,  four  of  which  go  to  the  sesamoid  bones,  one  to  each,  either  of  the 
two  external  ones  giving  off  a  band  which  winds  round  to  the  front,  and  joins 
the  tendon  of  the  extensor  proprius  of  the  digit,  while  two  other  bands  pass 
directly  from  the  ligament  through  the  interarticular  notch  of  the  metacarpus, 
separate  and  likewise  join  the  above-named  extensor  tendons  from  the  inside  ; 
two  slips  pass  down,  unite  and  become  attached  to  the  small  rudimentary 
digits  or  claws,  afterwards  separating  to  become  united  postero-superiorly  to 
the  distal  phalanges  ;  finally,  two  deep  branches  go  to  the  tendon  of  the  flexor 
perforatus  and  form  two  rings  through  which  passes  the  divided  tendon  of  the 
flexor  perforans.  The  inferior  sesamoid  ligaments  are  small,  and  consist  of  two 
lateral  bands,  which  attach  the  sesamoid  bones  to  the  head  of  the  proximal 
phalanx,  and  between  them  a  very  small  X  ligament.  The  intersesamoidean 
ligaments  are  three  in  number ;  there  is  one  between  each  pair  of  bones,  and 
one  joining  the  two  internal  ones.  A  common  annular  ligament  is  found 
about  the  region  of  the  fetlocks,  and  two  smaller  special  annular  ligaments 
lower  down.  (Fig.  87,  /  g  g'.)  The  superior  interdigital  ligament  is  crucial, 
and  situated  between  the  two  proximal  .phalanges,  in  small  ruminants  it  is  very 
rudimentary.  There  are  only  two  fibrous  bands  which  attach  the  glenoid 
cartilage  to  the  first  phalanx.  The  inferior  interdigital  ligament  joins  the 
distal  phalanges  and  navicular  bones  together,  and  in  the  ox  is  connected  with 
the  tendon  of  the  flexor  perfo.ans.  The  superior  navicular  ligament,  coming 
-from  the  mesian  phalanx,  is  formed  of  elastic  tissue. 

Pelvic  Limb. 

The  pubio-femoral  ligament  is  wanting  in  all  the  domesticated  animals  other 
than  the  horse  ;  the  absence  of  this  ligament  enables  the  larger  ruminants  to 
deliver  those  sweeping  circular  blows  with  the  foot,  which  are  known  by  the 
familiar  name  of  "cow-kicks."  There  is  only  one  stroAght  ligament  of  the 
patella  in  the  smaller  ruminants.  With  respect  to  the  tarsus,  we  may  remark, 
that  there  is  more  motion  in  that  joint  in  the  ruminant,  due  to  the  greater 
mobility  of  the  astragalus,  which  possesses  gliding  motion  upon  the  calcaneum, 
the  cubo-cuneiform  bone,  the  tibia,  and  the  malleolar  bone,  all  of  which  assist 
in  forming  the  mobile  portion  of  the  joint. 

In  the  elephant  there  is  no  roimd  ligament ;  and  the  femur  instead  of  being, 
when  at  rest,  inclined  downwards  and  forwards,  maintains  an  almost  perpen- 
dicular position  ;  this  accounts  for  the  peculiar  contour  of  the  haunch  in  that 
animal. 


CARNIVORA.  153 

OMNIVORA. 

AXIAL   SKELETON. 

In  tlie  hog  tlie  ligamentum  nuchce  can  scarcely  be  said  to  exist ;  a  fibrons 
cord  from  the  dorsal  spines  to  tbe  occiput  represents  it.  There  is  only  one 
synovial  capsule  in  the  occipito-atloid  joint,  and  there  is  a  transverse  odontoid 
ligament  which  passes  over  the  odontoid  process,  and  keeps  it  down  on  the 
floor  of  the  atloid  ring.  The  sternal  ribs  articulate  disl^lly  like  those  of  the 
ox,  and  the  remarks  on  the  sternal  articulations  of  that  animal  also  apply  to 
■the  hog.  The  temporo-maxillary  joint  possesses  great  motion  anteriorly  and 
posteriorly,  resembling  in  its  structure  that  of  the  rabbit,  the  anterior  mastoid 
process  being  small,  and  the  temporal  articular  surface  large.  The  ligaments 
between  the  hyoid  cornua  and  cornicula  are  elastic. 


APPENDICULAR  SKELETON. 

The  synovial  membrane  of  the  shoulder  joint  is  continued  into  the  bicipital 
groove.  In  the  elbow  joint  the  internal  lateral  ligament  is  shorter  than  the 
external  one.  The  radius  and  ulna  have  been  described  as  anchylosed  and 
also  as  closely  connected  by  fibrous  tissue.  Whichever  be  the  more  common 
mode  of  union,  there  is  no  motion  between  these  bones.  The  four  bones 
of  the  metacarpus  are  joined  by  prolongations  of  the  great  carpal  liga- 
ments above,  and  below  by  interarticular  ligaments.  Each  metacarpo- 
phalangeal joint  is  supplied  with  an  intersesamoid,  two  lateral,  a  crucial 
inferior  sesamoid,  and  an  anterior  capsular  ligament,  also  with  a  synovial 
membrane,  and  lateral  ligaments  for  the  joint  itself.  The  suspensory  liga- 
ment is  replaced  by  the  interosseous  palmar  muscles,  and  there  are  small 
superior  interdigital  ligaments  between  the  proximal  phalanges.  A  very  small 
osseous  nodule  is  usually  found  on  each  of  the  anterior  capsular  ligaments  of 
these  joints.  The  external  lateral  navicular  ligaments  resemble  those  of  the 
horse ;  the  internal  ones  are  wanting.  An  elastic  navicular  ligament  Like 
that  of  the  ox  is  found  in  the  large  digits. 

There  is  no  pubio-femoral  and  onlv  one  straioht  vaiellar  ligament.  The  tibio- 
fibular articulation  consists  of  an  amphiarthrosis  superiorly,  a  diarthrosis 
inferiorly,  and  between  these  an  interosseous  ligament,  stronger  below  than 
above.    The  tarsal  articulation  resembles  iu  the  main  that  of  the  ruminant. 


CARNIVORA. 

AXIAL    SKELETON. 

The  ligamentum  nuchce  is  represented  by  a  fibrous  band  which  is  larger  in 
the  dog  than  in  the  cat ;  in  the  cervical  vertebrae  of  the  former,  and  in  the 
vertebrae  generally  of  the  latter,  there  are  interspinous  muscles  instead  of  liga- 
ments. The  occipito-atloid  and  odontoid  ligaments  are  similar  to  those  of  the 
hog.  In  the  temporo-maxillary  joint  there  is  merely  ginglymoid  motion,  an^- 
the  meniscus  is  very  thin. 


154  COMPARATIVE  ARTHROLOGY. 

APPENDICTJLAK    SKELETON, 

la  the  camivora  the  synovial  membrane  of  shoulder  joint  is  similar  to 
that  of  the  hog  in  its  arranagement.  The  lateral  ligaments  of  the  elbow  joint, 
together  with  the  annular  ligament,  form  a  kind  of  ring  in  which  the  head  of  the 
radius  slightly  revolves,  as  there  is  a  certain  amount  of  motion  between  it  and 
the  ulna.  The  radio-ulnar  articulation  consists  of  a  superior  and  an  inferior 
rotatory  diarthrosis,  and  an  interosseotis  ligament ;  the  rotatory  movementB 
between  these  bones  are  termed  pronation  and  supination,  the  prone  being  the 
normal  position  of  the  extremity.  The  metacarpus  is  formed  similarly  to  that 
of  the  hog,  but  it  is  more  mobile,  and  the  rest  of  the  articulations  of  the  limb 
resemble  those  of  that  animal,  with  the  exception  of  the  distal  interphalangeal, 
where  we  find  anteriorly  an  elastic  ligament  which  acts  as  the  retractor  of  the 
claw,  and  is  stronger  and  much  more  active  in  the  cat  than  in  the  dog,  the 
claw  of  the  former  being  much  more  retractile.  Posteriorly  a  piece  of  fibro- 
cartilage  is  the  analogue  of  the  navicular  bone,  which  is  wanting. 

The  patella  has  one  straight  ligament,  and  the  menisci  are  united.  In  the 
tibio-fibular  articulation,  there  is  superiorly  a  diarthrosis,  otherwise  it  is  formed 
on  the  same  plan  as  that  of  the  hog,  as  is  the  tarsal  joint,  excepting  that  the 
astragalus  has  an  inferior  head  instead  of  a  trochlea. 


CHAPTER   III. 
MYOLOGY. 

The  branch  of  anatomy  which  treats  of  the  muscular  system  is 
called  Myology.  The  muscles  are  the  active  organs  of  motion,  or 
of  locomotion,  the  bones  and  ligaments  being  passive  organs  of 
^-he  same. 

Before  studying  the  muscles  individually  it  is  necessary  to  take 
a  brief  view  of  their  anatomical  and  histological  structure.  They 
contain  the  specific  contractile  substance  termed  muscular  tissue, 
together  with  areolar  and  fibrous  tissue,  and  a  certain  amount  of 
fatty  material ;  they  are  also  furnished  with  nerves,  blood-vessels, 
and  absorbents. 

MUSCULAR    TISSUE. 

Muscular  tissue  is  the  name  applied  to  contractile  fibres, 
which  are  either  collected  into  bundles  connected  at  their 
extremities,  and  forming  distinct  organs  termed  muscles,  to 
which  the  familiar  name  flesh  is  applied;  or  they  are  found 
helping  to  form  the  walls  of  the  hollow  viscera,  as  the  bladder, 
stomach,  &c. 

In  the  first  variety  the  fibre  presents,  when  magnified,  a  striped 
appearance,  the  stripes  being  placed  transversely ;  it  is  therefore 
known  as  striped  or  striated  fibre,  and  as  with  little  exception 
its  contraction  and  relaxation  are  controlled  by  the  will  of  the 
animal,  it  is  also  termed  voluntary  fibre  or  muscle.  The  second 
variety  differs  from  the  first  in  not  being  striped,  and  also  in  its 
action  being  beyond  the  control  of  the  will ;  hence  it  is  named 
non-striated  or  involuntary  fibre.  The  chief  exceptions  to  this 
general  distinction  occur  in  the  heart  and  in  the  upper  part  of 
the  oesophagus,  which  contain  'i-nvoluntary  striated  tissue.  Both 
varieties  are  red  in  colour,  but  +he  hue  of  the  striated  kind  is  far 
deeper.  We  therefore  describe  two  kinds  of  muscular  tissue,  the 
striated  and  the  non-striated. 

15ft 


156 


MYOLOGY. 


STRIA.TED    MUSCULAR    TISSUE. 

Voluntary  or  striated  muscular  tiasue  forms  tlie  mass  of  the 
so-called  muscles,  which  terminate  at  either  extremity  in  fibrous 
structures  termed  the  tendons,  by  means  of  which  they  are 
attached  to  the  bones  ;  the  intermediate  fleshy  portion  is  often 
called  the  belly  of  the  muscle.  A  muscle  is  composed  of  bundles, 
or  fasciculi  of  fibres,  which  are  the  integral  parts  of 
the  structure.  The  microscope  shows  these  fibres  to 
consist  of  fine  filaments  termed  fihrilloe,  which  run 
parallel  to  each  other,  maintaining  an  undivided 
course  throughout.  Each  fibre  is  enclosed  in  a 
delicate  tubular  sheath  called  the  sarcolemma  or 
inyolerartia,  composed  of  a  transparent  and  ap- 
parently homogeneous  membrane,  tough  and  elastic, 
which  isolates  each  fibre,  and  frequently  remains 
intact  after  rupture  of  its  contents.  The  fibres, 
about  "s^oth  of  an  inch  in  diameter,  are  gathered 
into  prismatic  or  polyhedral  fasciculi,  and  invested 
with  a  sheath  of  connective  tissue,  which  is  inflected 
between  the  fibres,  and  called  the  perimysium 
internum  ;  the  entire  muscle  has  likewise  an 
investing  sheath  of  connective  tissue,  the  peri- 
mysium externum,  continuous  with  the  above.      This  connective' 


Piu.  66. 
Fasciculus  of 
striated  muscu- 
lar fibres.  Trans- 
verse striae  seen 
at  a;  6,  Union  of 
fibres  with  the 
tendon. 


Fia.  67. 
A  single  striated  muscular  fibre,  showing  its  com- 
ponent fibriUse. 


tissue  is  membranous  in  structure,  its  use  being  to  connect  the 
bundles  and  fibres,  and  to  serve  as  a  matrix  for  the  ramification 
of  blood-vessels,  nerves,  and  absorbents. 

A  muscular  fibre,  examined  under  a  power  of  300  diameters 
or  less,  will  display  the  transverse  waving  strian  or  lines,  from 
which  the  name   "  striated  "  is  derived.      Longitudinal  markings,. 


NON-STRIATED    MUSCULAR    TISSUE.  157 

or  lines  are  also  often  apparent,  but  are  less  regular  than  the 
strige.  The  component  fibrillse  of  a  muscular  fibre  may  be  demon- 
strated by  macerating  the  tissue  in  strong  alcohol,  and  pressing 
the  prepared  object,  when  each  fibrilla  will  be  seen  to  consist  of 
a  row  of  alternately  light  and  dark  spots.  By  other  means,  such 
as  treatment  with  hydrochloric  acid,  or  by  a  smart  blow,  a 
muscular  fibre  may  be  separated  into  transverse  discs  correspond- 
ing to  its  striated  appearance.  These  two 
separations  of  a  fibre  have  been  termed  the 
longitudinal  and  transverse  cleavages.  Could 
both  these  operations  be  performed  on  the 
same  fibre,  the  result  would  be  a  crucial  cleav- 
age of  it  into  a  number  of  objects  which  would 
appear  under  a  high  power  as  dark  spots,  with 
light  spaces  round  them,  both  being  rectang- 
ular in  form  ;  they  are  known  as  the'  sarcous 
elements  of  Botvman,  and  in  them  rests  the 
inherent  -power  of  contractility.  Thus  a  trans- 
verse row  of  sarcous  elements  forms  a  disc  ; '  a 
longitudinal  row  a  fibrilla.  When  seen  through 
the  medium  of  the  sarcolemma  the  dark  spots 
appear  transversely  as  a  continuous  line,  hence 
the  striated  appearance    of   the    fibre.      The  fig.  68. 

fibres  cleave   more  readily  into  fibrilte   than     striated  muscular  fibres 

.     ,        T  from  the  Horse. 

into  discs. 

Modern  observation  modifies  the  above,  the  fibre  being  gener- 
ally regarded  as  a  series  of  alternate  light  and  dark  discs,  the 
latter  having  on  each  transverse  surface  a  number  of  darker 
granules,  connected  by  fine  longitudinal  and  transverse  lines. 
The  former  with  their  nodular  extremities  are  termed  muscle-rods. 
A  number  of  oval  objects,  related  with  the  sarcolemma,  appear 
on  treating  a  fibre  with  acetic  acid ;  these  are  the  muscle 
corpuscles,  and  they  are  nucleated.  Striated  fibres  are  for  the 
most  part  isolated,  but  those  of  the  heart,  which,  as  already 
stated,  are  involuntary,  divide  into  branches,  and  the  branches 
of  different  fibres  frequently  join,  or,  as  it  is  termed,  anastomose. 
(Fig.  152.) 

NON-STRIATED    MUSCULAR   TISSUE. 

Involuntary  or  non-striated  muscular  tissue  is  pale  in  colour, 
and  consists  of  fibres,  bound  into  fasciculi  by  a  fine  perimysium  of 
areolar  tissue. 

The  fibres  never  terminate  in  tendons,  and  are  not  invested  in 
a  sarcolemma ;  they  are  cylindrical  in  >  shape,  and  composed   of 


158 


MYOLOGY. 


fusiform  or  elongated  cells,  which  become  apparent  after  macer- 
ation of  the  tissue  in  dilute  hydrochloric  acid  or  other  reagents, 
or  it  may  be  without  any  such  preparation.  These  cells  are 
the  contractile  cells  of  Kolliker,  and  in  them  au  elongated  nucleus 
may  be  visible.  The  fasciculi  vary  very  greatly  in  size  in  dif- 
ferent situations,  and  often  crossing  each  other,  they  give  the- 
tissue  in  some  parts  a  mesh-like  appearance.  The  non-striped, 
tissue  is  very  abundant,  being  found  in  the  walls  of  the  ali- 
mentary canal  and  hollow  viscera,  in  gland  ducts,  in  the 
coats  of  blood-vessels,  in  the  skin,  and 
elsewhere. 

Both  varieties  of  muscular  tissue  are 
plentifully  supplied  with  blood,  and  in  stri- 
ated tissue  the  capillaries  or  minute  blood- 
vessels are  arranged  longitudinally  with 
transverse  connecting  branches,  but  they 
do  not  penetrate  the  sarcolemma,  they  and 
the  larger  vessels  alike  being  found  in  the 
perimysium  or  interstitial  connective  tissue. 
The  striated  tissue  is  supplied  with  nerves 
from  the  cerebro-spinal  system,  but  the  non- 
striated  tissue  receives  its  supply  from  the 
sympathetic  system,  and  the  vital  stimulus 
conveyed  by  either  of  these  causes  the  contraction  of  the  fibres. 

The  description  of  the  arrangement  of  involuntary  tissue  forms 
no  part  of  the  present  section  of  our  subject  ;  the  tissue  is 
described  here  chiefly  in  order  that  its  structure  may  be  com- 
pared with  that  of  the  voluntary  kind. 

TENDONS. 

The  tendons  in  which  voluntary  muscles  terminate  at  either 
end  are  structures  resembling  ligaments  in  their  composition, 
being  formed  of  white  fibrous  tissue  mixed  with  yellow  fibres. 
Like  ligaments,  they  are  practically  non-elastic,  and  while  they 
attach  the  muscles  to  the  bones,  they  merely  transmit  the  action 
of  the  former  to  the  latter,  and  are  therefore  passive  instruments 
of  motion. 

The  extremity  of  a  muscle  which  has  the  most  fixed  attachment 
is  called  its  origin ;  the  other  extremity  attached  to  the  more 
movable  structure,  its  insertion.  The  tendon  of  insertion  is 
often  longer  than  that  of  origin,  which  is  frequently  rudimentary. 
In  some  cases  both  extremities  are  equally  movable. 


YiQ.  69. 
A,  Non-striated  muscular 
fibres;  a  a.  The  component 
fusiform  cells;  6,  6,  The 
nuclei.  B  and  C,  Single  cells 
mora  highly  magnified;  C 
having  been  treated  with 
acetic  acid. 


FASCIA.  159 

The  strongest  part  of  a  muscle  is  its  point  of  union  with  the 
tendon,  but  the  manner  in  which  that  union  is  effected  is  not 
satisfactorily  explained.  According  to  some  authorities,  the 
muscular  fibres  are  prolonged  into  the  connective  tissue  of  the 
tendon ;  or,  "  the  contractile  fibre  terminates  in  a  rounded  ex- 
tremity which  is  buried  in  a  corresponding  depression  in  the 
tendon"  (Chauveau).  The  sarcolemma  and  the  areolar  tissue, 
both  of  the  fibre  and  tendon,  are  no  doubt  instrumental  in 
effecting  the  union. 

Tendons  often  send  processes  into  the  substance  of  the 
muscle,  which  may  extend  throughout  its  length  ;  such  pro- 
cesses are  described  as  tendinous  intersections ;  they  also 
appear  to  send  small  fibres  into  the  substance  of  the  bones  to 
which  they  are  attached.  Tendons  vary  in  form,  size,  and 
density,  but  all  are  either  rounded  or  flattened.  The  former 
are  funicular,  the  latter  aidoneurotic  tendons ;  in  either  form 
their  use  is  the  same.  They  become  attached  to  bones  through 
the  medium  of  the  periosteum,  sometimes  expanding  to 
strengthen  its  outer  layer. 

FASCIA. 

Each  group  of  muscles  is  invested  and  bound  down  by  a  strong 
membranous  expansion  of  white  fibrous  tissue,  called  fascia, 
which  is  firmly  connected  with  the  bone.  This  ternri  is  however 
applied  to  other  membranous  expansions,  differing  very  materially 
in  strength,  texture,  and  relations.  For  example,  beloAV  the 
skin  and  panniculus  there  is  a  membranous  expansion,  which 
forms  a  continuous  covering  over  the  whole  body,  composed 
of  connective  tissue  more  or  less  condensed.  Hence  fasciae  have 
been  divided  into  superficial,  and  deep  or  aponeurotic. 

Superficial  fascia  consists  of  cellular  and  elastic  tissue,  varying 
in  thickness  in  different  regions  of  the  body.  Where  the  skin  is 
loose  it  is  most  distinct ;  and  sometimes  it  is  inseparable  from  the 
muscles  and  skin,  as  in  the  eyelids  and  lips.  Its  meshes  may  be 
filled  with  adipose  cells,  or  condensed  so  as  to  form  a  fibro-cellular 
membrane  destitute  of  fat.  Its  use  is  to  connect  and  protect 
the  various  structures  it  contacts,  and  to  furnish  a  matrix  for 
blood-vessels ;  the  fat  in  the  subcutaneous  fascia  helps  to  conserve 
the  animal  heat,  fat  being  a  bad  conductor. 

Aponeurotic  fascia  not  only  covers,  supports,  and  binds  down 
the  groups  of  muscles,  but  affords  processes  between  them,  and 
becomes  united  to,  and  blended  with,  the  periosteum.      Some  of 


160 


isSYOLOGY, 


these  fasciae  have  distinct  muscles  for  rendering  them  tense,  a» 
the  tensor  fasciae  latse.  Fasciae  are  also  found  in  connection 
with  the  walls  of  cavities,  as  in  the  pelvis. 

In  the  limbs,  where  the  muscular  bellies  form  lengthy  masses, 
with  long  tendons  attached  at  considerable  distances,  there  would 
be  considerable  displacement  during  motion,  were  it  not  that  in 
these  parts  the  fascia  is  very  strong,  enclosing  the  body  of  each 
muscle  in  a  sheath,  as  also  each  group  of  muscles. 

MUSCULAK  NOMENCLATURE. 

Musculai"  nomenclature  •  is  unsatisfactory  and  confused,  some 
muscles  being  named  from  their  form,  as  Trapezium,  Rhomboideus, 
Scalenus  ;  others  from  their  use,  as  Flexor,  Extensor,  Adductor, 
Abductor,  &c. ;  some  from  their  direction,  as  Rectus,  Transversus, 
Obliquus ;  others  from  their  situation,  as  Temporalis,  Peroneus, 
Subscapularis ;  some  again  from  their  attachments,  as  Stemo- 
maxillaris,  Coraco-radialis,  and  Stylo-hyoideus ;  and  some  from 
their  homologues  in  the  human  subject.  A  muscle  may  have  a 
physiological  name  expressing  its  use,  and  an  anatomical  one 
alluding  to  some  feature  in  its  morphology  ;  but  perhaps  the  most 
satisfactory  system  of  nomenclature  is  that  which  names  muscles 
from  their  attachments. 

Muscles  vary  so  much  in  shape  that  no  classification  of  them 
can  be  based  on  that  feature.  Some  of  them,  however,  present 
such  marked  features  that  certain  terms  are  used  to  describe  their 
form.  Thus,  biceps  and  triceps  express  a  two  or  three-headed 
muscle ;  a  diagastric  muscle  has  two  bellies,  joined  by  a  mesian 
tendon  ;  a  radiating^  muscle  consists  of  bundles  diverging  from  a 
point  of  attachment ;  ia  pen/niform  muscle  resembles  a  feather  in 
shape,  and  a  semipenniform  one  the  lateral  half  of  the  same,  the 
tendon  corresponding  to  the  axis  or  scapus  of  the  feather. 

In  the  descriptions  of  muscles  which  follow,  the  names  printed 
in  small  capitals  are  those  most  commonly  in  use  in  Great 
Britain,  whereas  the  names  below,  and  in  italics,  are  almost 
uniformly  anatomical,  expressing  in  most  cases  the  places  of 
attachment  of  the  muscles, — a  nomenclature  more  valuable 
though  less  current  than  the  one  in  use. 

CLASSIFICATION  OF  MUSCLES. 

Either  an  Anatomical  or  Physiological  mode  of  classification 
can  be  applied  to  the  muscular  system,  but  the  former  is  of 
course  the  one  adopted  here.     Again,  muscles  may  be  classed 


EXPLiVNATION  OF  PLATE  11. 
Muscles  of  the  Horse. 

Superficial  Layer. 
The  panniculus  and  tunica  dbdomitialis  are  removed. 


1.  Abducens, 

33.  Extensor  metacarpi  maguus» 

2.  Retrahentes  muscles. 

34-  Humeralis  obliquus. 

2'.  AttoUens  maximus. 

35.  Extensor  pedis. 

2".  Attollens  anticus. 

36.  Flexor    metacarpi    externus  avA 

3.  Temporalis. 

medius. 

4.  Nasalis  longus. 

37.  Flexor  metacarpi  intemus. 

5.  Orbicularis  palpebrarum. 

46.  Cervical  1 

47,  Dorsal    ]  ^'^^^^^' ^^^^' 

6.  Levator   labii  superioris    alseque 

nasi. 

48,  Rhomboideus  longus. 

7.  Dilatator  naris  lateralis. 

49,  Superficialis  costarum. 

8.  Orbicularis  oris. 

50,  Splenius. 

9.  Zygomaticus. 

52,  lutercostales. 

9'.  Buccinator, 

54,  Tensor  fasciae  latoe. 

10.  Depressor  labii  inferioris. 

55,  Triceps  abductor  femoris. 

11.  Masseter. 

56,  Gluteus  externus. 

12.  Levator  humeri. 

61,  Biceps  rotator  tibialis. 

13.  Trapezius  cervicalis. 

62,  Rectus  femoris. 

14.  Trapezius  dorsalis. 

63.  Vastus  externus. 

15.  Latissimus  dorsi. 

65,  Gastrocnemius 

18.  Pectoralis  parvus. 

68.  Flexor  pedis  perforans. 

19.  Pectoralis  magnus. 

69.  Peroneus. 

20.  Sterno-maxillaris. 

70.  Extensor  pedis. 

23.  Subscapulo-byoideus. 

71.  Flexor  metatarsi. 

24.  Antea-spinatus, 

72.  Flexor  pedis  accessorius. 

25,  Teres  externus. 

74.  Obliquus  abdominis  «xtemu8» 

26,  Postea-spinatus. 

30.  Caput  medium  \  of  the  triceps 

31.  Caput  magnum /extensor  bracbii. 

PANNICULUS   CARNOSUS.  ^"■*- 

anatomically  either  according  to  their  attachments  or  to  the 
regions  their  fleshy  portions  chiefly  cover.  Although  a  nom^- 
clature  based  upon  the  attachments  of  muscles  is  most  valuable, 
a  descriptive  classification  so  constructed  would  lead  to  confusion, 
hence  we  group  the  muscles  according  to  the  regions  they  mamly 
occupy,  and  divide  them  primarily  into  those  covering  each  of 
the  following  regions  : — 

Subcutaneous  region. 

Head. 

Trunk. 

Pectoral  limb. 

Pelvic  limb. 

We  shall  describe  them  in  the  above  order,  subdividing  each 
region  as  may  be  necessary. 


Muscles. 

subcutaneous  region. 

panniculus  carnosus. 

(Musculus  Suhcutaneus.) 

After  carefully  removing  the  skin  and  subcutaneous  cellular 
tissue,  the  first  muscle  which  presents  itself  is  one  peculiar  to 
quadrupeds,  the  Panniculus  carnosus.  This  muscle  is  spread 
over  the  greater  part  of  the  body,  and  may  be  divided  into  facial, 
cervical,  thoracic,  and  abdominal  portions,  but  as  these  are  con- 
tinuous with  each  other,  we  can  conveniently  describe  the  whole 
as  a  single  structure.  The  panniculus,  as  a  whole,  is  aponeurotic 
superiorly,  becoming  more  and  more  fleshy  as  it  descends.  It  is 
firmly  attached  to  the  skin  by  connective  tissue. 

The  facial  portion  consists  of  an  aponeurotic  expansion,  which 
becomes  muscular  over  the  muscles  situated  below  and  before  the 
zygoma.  Its  fibres  are  arranged  in  a  divergent  manner,  radiating 
from  the  angle  of  the  maxilla,  and  a  portion  is  inserted  to  the 
orbicular  muscle  of  the  mouth,  forming  the  Retractor  anguli  oris 
(Risorius  Santorini).  Posteriorly  it  unites  with  the  cervical  por- 
tion, which  is  likewise  chiefly  aponeurotic,  commencing  in 
iront  of  the  neck  by  a  thin  muscular  band,  it  joins  its 
in  fellow  the  median  line  by  a  fibrous  raphe,  and  covers  the 
muscles   of    the  inferior  cervical  region.     Above  it  becomes 

M 


162  MYOLOGfY. 

aponeurotic,  and  is  attached  to  the  ligamentum  nuchse,  while 
infero-laterally  it  becomes  more  fleshy,  and  is  inserted  to  the 
anterior  portion  of  the  cariniform  cartilage  ;  some  describe  this 
portion  as  a  part  of  the  Levator  humeri,  the  panniculus  being 
firmly  blended  with  that  muscle  inferiorly.  The  thoracic  portion 
is  continuous  with  the  cervical  at  the  sternum,  and  passes  over 
the  front  of  the  shoulder  superiorly,  covering  its  external  side ; 
it  is  attached  to  the  dorsal  spines  together  with  the  trapezius. 
The  abdominal  portion  forms  a  broad  oval-shaped  fleshy  expan- 
sion, its  fibres  running  from  the  flank  to  the  shoulder ;  it  is 
thick  and  fleshy  behind  the  arm,  where  it  has  a  well-marked, 
flat  tendinous  attachment  to  the  skin,  and  below  which  a  ten- 
dinous expansion  penetrates  between  the  chest  and  the  limb,  and 
is  attached  to  the  Pectoralis  magnus  and  internal  trochanter  oi 
the  humerus.  Posteriorly,  by  a  strong  band,  fleshy  and  apon- 
eurotic, it  reaches  the  stifle  joint  and  fascia  of  the  thigh } 
above,  it  reaches  the  lumbar  and  dorsal  spines,  and  below  it 
becomes  blended  with  the  abdominal  fascia. 

Relation. — It  is  related  externally  with  the  skin  ;  internally 
with  the  superficial  layer  of  muscles. 

Action. — It  corrugates  the  skin,  and  thus  enables  the  animal 
to  expel  insects  and  irritating  bodies,  its  use  being  thus  protec- 
tive ;  to  some  extent  it  also  supports  and  binds  down  the  subja- 
cent muscles. 

The  Head. 

The  muscles  of  this  region  may  be  divided  into  the  following 
groups : — 

Anterior  maxillary. 
Posterior  maxillary. 
Hyoidean. 
Palpebral. 
Auricular. 

In  addition  to  these  we  have  the  Glossal,  Pharyngeal,  and 
Laryngeal  groups  also  associated  with  the  head;  the  two  first  of 
these  will  be  more  appropriately  described  hereafter  when  treat- 
ing of  the  Tongue  and  Pharynx,  and  the  last  along  with  the 
Larynx. 


ANTERIOR    MAXILLARY    GROUP.  IBS' 


ANTERIOR  MAXILLARY  GROUP. 


In  the  broad  sense  this  group  occupies  the  anterior  half  of  the 
skull,  certain  of  the  muscles  extending  further  backwards;  it 
consists  of  the  followins:  muscles  :  — 


Zygomaticus. 

Buccinator. 

Orbicularis  oris. 

Levator  labii  superioris  alaeque 

Nasalis  longus.  [nasi. 

Dilatator  naris  lateralis. 


Dilatator  naris  transversus. 
Dilatator  naris  inferioris. 
Dilatator  naris  superioris. 
Depressor  labii  superioris. 
Levator  labii  inferioris. 
Depressor  labii  inferioris. 


ZYGOMATICUS. 

{Z ygomatico-lahialis.) 

(PL.  XL  9.) 

A  ribbon-shaped  muscle,  very  pale  and  small,  situated  on  the 
side  of  the  face,  its  fibres  extending  forwards. 

Attachments. — It  arises  from  the  fascia  of  the  masseter,  near 
the  anterior  aspect  of  the  maxillary  spine,  being  blended  with 
the  panniculus,  and  is  inserted  near  the  angle  of  the  mouth,  its 
fibres  blending  with  the  buccinator. 

Action. — It  retracts  the  angle  of  the  mouth. 


BUCCINATOR. 

(Alveolo-Iabialls.) 

(Pl.  II.  9'.     Fig.  70.  i.) 

Situated  on  the  side  of  the  face,  covering  the  diastema  and' 
molar  teeth,  this  muscle  is  flat  and  thin,  and  consists  of  two 
layers,  sometimes  described  as  separate  muscks. 

Attoxhments. — The  internal  layer  arises,  under  the  masseter, 
from  the  alveolar  tuberosity,  and  alveoli  of  the  molar  teeth  of 
both  jaws,  and  blends  with  the  orbicularis  oris.  The  external 
layer  exists  only  anteriorly,  and  is  peuniform,  its  fibres  being 
inserted  along  the  interdental  spaces. 

Relations. — This  muscle  is  related  superiorly  with  the  molar 
glands,  postero-externally  with  the  masseter,  and  internally  with, 
the  buccal  membrane. 


164.  MYOLOGY. 

Action. — It  retracts  the  angle  of  the  mouth,  but  specially 
serves  to  force  the  food  between  the  molars,  and  to  prevent  the 
buccal  membrane  from  bemg  injured  by  the  latter. 

ORBICULARIS  ORIS. 
(Labialis.) 
(Pl.  II.  8.) 

This  is  a  sphincter  or  annular  constrictor  muscle,  and  as  such 
has  virtually  neither  origin  nor  insertion  ;  surrounding  the  mouth 
and  forming  the  substance  of  the  lips,  it  is  separable  into  two 
layers,  and  is  related  internally  with  the  mucous  membrane  of 
the  mouth  and  the  labial  glands,  and  externally  with  the  skin, 
to  which  it  is  firmly  adherent.  It  is  the  intrinsic  muscle  of  the 
lips,  and  receives  for  the  most  part  the  insertions  of  the  extrinsic 
muscles. 

Action. — It  is  the  constrictor  of  the  anterior  aperture  of  the 
mouth,  and  also  assists  in  mastication,  suction,  and  prehension  of 
food. 

LEVATOR  LABII  SUPERIORIS  AL^ffiQUE  NASL 

(Supernaso-lahialis. ) 
(Pl.  II.  6.) 

Situated  superiorly,  on  the  side  of  the  cheek,  running  forward? 
and  downwards,  this  muscle  is  long,  flat,  and  aponeurotic  supe- 
liorly,  dividing  into  two  unequal  bands,  between  which  passes 
the  dilatator  naris  lateralis. 

Origin. — It  arises  from  the  frontal  and  nasal  bones,  the 
anterior  division,  the  larger  and  thicker,  passing  under  the  dila- 
tator above  named. 

Insertion. — To  the  nostril  and  upper  lip,  thfe  posterior  divi- 
sion reaching  the  angle  of  the  mouth. 

Action. — It  raises  the  upper  lip  and  angle  of  the  mouth,  and 
dilates  the  nostril. 

NASALIS  LONGUS. 

(Supermaxillo-Iabialis. ) 

(PL.  II.  4.     Fig.  70.  g.) 

Situated  below  the  preceding  muscle,  this  muscle  runs  hori- 
zontally forwards.  In  shape  it  is  pjTamidal,  with  a  fleshy  belly 
and  a  long  tendon  of  insertion. 


NASAL    MUSCLES. 


165 


Origin. — It  arises  from  the  surface  of  the  superior  maxilla,  at 
its  junction  with  the  malar  and  lachrymal  bones. 

Insertion. — The  tendon  passes  to  the  extremity  of  thB  nose, 
where,  joining  its  fellow,  it  forms  a  radiating  expansion,  becoming 
lost  in  the  upper  lip. 

Action. — It  elevates  and  corrugates  the  upper  lip,  if  acting 
.with  its  fellow  ;  if  acting  alone,  it  pulls  the  lip  to  one  side. 


Fig.  70. 
Muscles  of  tuf  he<*d-Un  lateral  view,  a,  Abducens  ;  6  c  d,  Scuto-auriculaxis 
externus,  inferior,  ^id-^Te,  svBd  superior  portions  ;  e,  Levator  palpebrae  superioris 
extemus;  / /,  O.bicuiaris  palpebrarum;;  g,  Nasalia  longus  ;  h.  Depressor  labil 
inferioris';  i,  Buccinc^tor ;  ;:,  Masseter ;  I,  Dilatator  naris  lateralis ;  m,  Dilatator 
naris  inferior!?  ;  n.  Dilatator  na^is  superioris. 


DILATATOU   iJ  rJ.-clS   LATERALIS. 

(Pyramidalis — Superr^uxillo-nasalis  Magnus. ) 

(PL.  II.  7.    no.  70. 1.) 

This  muscle  is  situated  on  the  side  of  the  cheek,  between  the 
branches  of  the  levator  labii  superioris,  extending  horizontally  ;  it 
has  a  flat  belly  and  tendon  of  origin. 

Attachments. — It  arises  from  the  anterior  extremity  of  the 
maxillary  spine  ;  it  is  inserted  to  the  side  of  the  nostril  and  the 
upper  lip,  blending  with  the  orbicularis  oris. 

Action. — It  dilates  the  nostril,  acting  on  its  external  wing. 


166  MYOLOGr. 


DILATATOR.  NARIS  TRANSVERSALIS. 
(Ifaso  transversalis.) 

Situated  at  the  supero-anterior  extremity  of  the  nose,  in  front 
o{  the  nostrils,  it  is  single,  flat,  and  four-sided,  consisting  of 
transverse  fibres  which  cross  each  other. 

Origin. — The  nasal  peak. 

Insertion. — The  superior  surface  of  the  cartilaginous  alee  of 
the  nostrils. 

Action. — It  dilates  the  nostrils. 


DILATATOR   NARIS   INFERIORIS. 
(Fig.  70.  m.) 
i^Nasalis  Brevis  Labii  Superioris — Supermaxillo-nasalis  Brevis.) 

Another  long  and  four-sided  muscle,  situated  at  the  side  of, 
and  a  little  behind  the  nostrils. 

Origin. — It  arises  by  an  aponeurotic  origin  from  the  upper 
free  margin  of  the  superior  maxilla  and  premaxilla. 

Insertion. — The  skin  of  the  false  nostril. 

Action. — It  dilates  the  nostril. 


DILATATOR   NARIS    SUPERIORIS. 
(Fig.  70.  n.) 

Situated  just  above  the  preceding,  it  is  broad  and  thin,  with 
ttponeurotic  attachments. 

Origin. — From  the  lateral  surface  of  the  free  margin  of  the 
2iasal  bone. 

Insertion. — The  skin  of  the  false  nostril. 

Action. — To  assist  the  preceding  muscle. 


DEPRESSOR   LABII   SUPERIORIS. 

Situated  on  the  mner  surface  of  the  upper  lip,  covered  by 
mucous  membrane,  it  is  thin  and  fleshy. 

Origin. — From  the  premaxilla  at  the  alveoli,  extending  from 
the  lateral  incisors  to  the  tushes. 

Insertion. — The  diverging  fibres  pass  obliquely  forwards  to 
l)lend  with  the  upper  lip  and  nasal  cartilages. 


POSTERIOR    MAXILLARY    GROUP.  167 

Action. — It  compresses  the  upper  lip,  and  perhaps  assists  in 
dilating  the  nostril. 

LEVATOR   LABII   INFERIORIS. 
(Levator  Menti.) 

Situated  on  the  inner  surface  of  the  under  lip,  below  the 
mucous  membrane,  it  is  like  the  preceding  in  shape. 

Origin. — From  the  alveoli  of  the  inferior  maxilla,  between  the 
lateral  incisors  and  tushes. 

Insertion. — The  under  lip  by  diverging  fibres. 

Action. — It  elevates  the  under  lip  and  chin,  and  presses  the 
lip  on  the  teeth. 

DEPRESSOR   LABII    INFERIORIS. 

(Maxillo-labialis. ) 

(PL.  II.  10.    Fig.  70.  h.) 

Situated  along  the  surface  of  the  lower  jaw,  it  is  in  shape  long 
and  pyramidal. 

Origin. — Posteriorly,  in  common  with  the  buccinator,  from 
the  alveolar  tuberosity,  and  the  superior  border  of  the  inferior 
maxilla,  behind  the  molar  alveoli. 

Insertion. — The  infero-lateral  part  of  the  under  lip  by  a  flat 
tendon. 

Action.^ — To  depress  the  under  lip. 

Posterior  Maxillary  Group. 

The  muscles  constituting  this  group  are  chiefly  those  of.  masti- 
cation, which  act  upon  the  temporo-maxillary  joint.  They  are  as 
follows  : — 


Masseter. 

Temporalis. 

Stylo-maxillaris. 


Pterygoideus  intemus. 
Pterygoideus  externus. 
Digastricus. 


*  [While  dissecting  at  the  Edinburgh  Veterinary  College  in  December,  1868, 
I  was  particularly  struck  with  the  action  of  this  muscle  ;  its  tendon  subdivides 
in  the  areolar  and  muscular  tissue  of  chin  and  posterior  lip,  and  its  action  is 
not  quite  to  depress  the  under  lip,  but  to  elevate  the  chin  and  lower  lip,  and 
thus  separate  the  lower  lip  from  the  lower  incisors.  This  is  the  opinion,  I  find, 
recorded  by  the  late  Professor  Goodsir  in  his  posthumous  manuscript. — En., 
Mrst  Edition.] 


168 


MASSETEE. 

(Zygomatico-maxillaris. ) 

(Pl.  II.  11.    Fig.  70.  h) 

Situated  on  the  posterior  part  of  the  cheek,  of  which  it  forms 
the  large  fleshy  portion,  it  is  broad,  thick,  flat,  and  irregularly 
four-sided,  consisting  of  several  layers,  intersected  by  tendinous 
bands,  and  enclosed  in  a  strong  a,poneurosis. 

Origin. — From  the  zygoma,  the  spine  and  external  surface  of 
the  superior  maxilla. 

Insertion. — The  outer  surface,  posterior  border,  and  angle  of 
the  inferior  maxilla. 

Relation. — Externally  with  the  facial  panniculus.  Over  its 
surface  are  distributed  the  facial  nerves,  and  along  its  anterior 
border  lies  the  parotid  duct,  and  the  facial  artery  and  vein ; 
buried  beneath  its  substance  is  the  alveolar  vein  or  vena  varicosa. 

Action. — To  elevate  the  lower  jaw  and  close  the  mouth,  being 
an  important  muscle  in  mastication. 

TEMPORALIS. 

{Temporo-maxillaris. ) 

(Pls.  II.  3  ;  III.  L) 

Situated  in  the  temporal  fossa,  which  it  fills,  this  muscle  is 
strong  and  fleshy,  intersected  by  tendon,  and  covered  by  fascia. 

Origin. — From  the  parietal  ridge,  and  part  of  the  occipital 
crest,  the  zygomatic  process  of  the  temporal  and  the  external 
surface  of  the  parietal  bones. 

Insertion. — The  coronoid  process  of  the  inferior  maxilla. 

Relation. — Externally  with  the  muscles  of  the  ear,  and  the 
scutiform  cartilage ;  inferiorly  with  the  pterygoid  muscles.  A 
pad  of  fat  lies  between  it  and  the  orbital  fossa. 

Action. — With  its  fellow  it  assists  in  closing  the  mouth  j  singly 
it  gives  slight  lateral  motion  to  the  lower  jaw. 

STTLO-MAXILLARIS. 
(Pl.  III.  1'.) 

Situated  behind  the  lower  jaw,  it  is  pyramidal  and  fleshy. 
Origin. — From  the  styloid  process  of  the  occiput. 


POSTERIOR    MAXILLARY    GROUP.  169 

Insertion. — The  posterior  angle  and  inner  margin  of  the  lower 
jaw. 

Relation. — Externally  with  the  parotid  gland;  internally  with 
the  guttural  pouch. 

Action. — It  depresses  the  lower  jaw  and  draws  it  backwards. 


PTERYGOIDEUS  INTERNUS. 
{Masseter  Internus — Spheno-maxillaris.) 

Situated  on  the  inner  surface  of  the  lower  jaw,  in  the  maxillary 
space,  corresponding  internally  to  the  masseter,  it  is  strong  and 
fleshy,  with  numerous  tendinous  intersections. 

Origin. — From  the  pterygoid  process  of  the  sphenoid  bone, 
and  the  palatine  ridge. 

Insertion. — The  inner  posterior  border  and  angle  of  the  inferior 
maxilla. 

Relation. — Posteriorly  with  the  pterygoideus  externus  and 
temporalis;  internally  with  the  guttural  pouch,  the  hyoid  bone, 
and  its  muscles ;  externally  with  the  ramus  of  the  maxilla  and 
the  inferior,  maxillary  nerve  and  vessels. 

Action. — Acting  with  its  fellow,  it  raises  the  jaw  and  closes 
the  mouth  ;  when  acting  singly,  it  produces  lateral  motion. 


PYTERYGOIDEUS   EXTERNUS 
(^Part  of  Spheno-maxillaris.) 

Situated  behind  the  preceding,  on  the  front  and  inner  side  of 
the  temporo-maxillary  articulation,  it  is  short,  thick,  and  fleshy, 
with  slight  tendinous  intersections. 

Origin. — From  the  ala  and  pterygoid  process  of  the  sphenoid 
bone. 

Insertion. — Passing  backwards  and  downwards,  it  reaches  a 
roughed  depression  on  the  inner  side  of  the  inferior  maxilla, 
just  below  its  condyle. 

Relation. — With  the  temporalis  and  the  pyterygoideus  inter- 
nus, which  is  below  and  before  it. 

Action. — It  assists  the  internus,  and  also  draws  the  lowe^f  jaw 
forwards,  antagonising  the  stylo-maxillaris. 


170  MYOLOGY. 


DIGASTRICUS. 


Situated  along  the  inner  surface  of  the  lower  jaw,  in  the 
maxillary  space,  it  contains  two  fleshy  bellies,  united  by  a 
merliflii  tendon. 

Origin. — From  the  styloid  process  of  the  occipital  bone. 

Insertion. — By  a  diffused  tendon  to  the  inner  surface  of  the 
lower  jaw,  towards  its  symphysis ;  the  mesian  tendon  plays 
through  a  groove  formed  by  the  tendon  of  the  hyoideus  magnus, 
at  the  body  of  the  hyoid  bone.  The  posterior  belly  gives  off 
also  a  bundle  which  is  inserted  to  the  posterior  border  of  the 
ramus,  considerably  above  the  angle. 

Action.— li  elevates  the  hyoid  bone,  retracts  and  depresses 
the  inferior  maxilla. 

Hyoid EAN  Group. 

The  muscles  of  this  group  are  six  in  number  and  they  act 
chiefly  upon  the  hyoid  series  of  bones.  Their  names  are  as 
follows  : — 


Mylo-byoideus. 
Gemo-hyoideus. 
Hyoideus  magnus. 


Hyoideus  parvus. 
Hyoideus  transversus. 
Stylo-hyoideus. 


MYLO-HYOroEUS. 

Situated  in  the  maxillary  space,  along  the  inner  side  of  the 
lower  jaw,  it  is  broad,  flat,  and  pennifbrm,  and  attached  to  a  line 
running  along  the  inferior  maxilla,  just  below  the  alveolar  pro- 
cesses ;  extending  forwards  as  far  as  the  symphysis,  and  to  the 
inferior  surface  of  the  body  and  spur  process  of  the  hyoid  bone, 
it  meets  its  fellow  of  the  opposite  side  in  the  median, line. 

Relation. — Externally  with  the  inferior  maxilla,  the  digastri- 
cus  and  the  lymphatic  glands  ;  internally  with  the  sublingual 
gland,  Wharton's  canal,  the  genio-hyoideus,  hyo-glossus  longus, 
genio-hyo-glossus,  and  the  hypoglossal  and  lingual  nerves  ; 
posteriorly  with  the  pterygoidei-muscles. 

Action. — By  drawing  the  os  hyoides  upwards  and  forwards  it 
elevates  the  tongue,  forming  a  kind  of  muscular  sling  in  which 
the  latter  or^an  lies. 


HYOIDEAN    GROUP.  171 


GENIO-HYOIDEUS. 
(Fig.  71.  e.) 

Covered  by  the  preceding  muscle,  this  is  long,  fusiform,  and 
tendinous  at  its  extremities. 

Origin. — From  the  lower  jaw,  near  its  symphysis. 

Insertion. — The  free  extremity  of  the  spur  process  of  the  os 
hyoides. 

Relation. — Externally  with  the  preceding  muscle,  superiorly 
■with  the  genio-hyo-glossus,  and  internally  with  its  fellow. 


'    Muscles  of  the  maxillary  space— infero-lateral  view.    Stractures  removed  from  the  right  side. 
«,  Genio-hyoideus ;  /,  Stylo-hyoideus ;   g,  Hyoideus  magnua. 

Action. — It  draws  the  os  hyoides  towards  the  anterio-inferior 
part  of  the  maxillary  space. 


HYOIDEUS  MAGNUS. 

{Kerato-hyoideus  Magnus.) 

(Fig.  71.  g.) 

Situated  on  the  outer  side  of  the  pharynx,  larynx,  and 
;guttural  pouch,  behind  the  comu  of  the  os  hyoides  and  running 
in  the  same  direction,  it  is  thin,  fusiform,  and  tendinous  at 
either  extremity. 

Origin. — From  the  postero-inferior  angle  of  the  comu  of  the 
OS  hyoides. 


172 


MYOLOGY. 


Insertion. — To  a  small  tubercle  on  the  heel  process  of  the  os 
hyoides. 

Relation. — Externally  with  the  pterygoid  muscle  ;  internally 
with  the  pharynx,  guttural  pouch,  and  hypoglossal  nerve;  the 
glosso-facial  artery  and  glosso-pharyngeal  nerve  pass  between  it 
and  the  comu.  The  anterior  tendon  forms  a  ring  through  which 
plays  the  middle  tendon  of  digastricus. 

Action. — It  draws  the  body  of  the  os  hyoides  backwards  ana 
upwards,  thus  antagonising  the  preceding  muscle  ;  it  also  assists 
in  dilating  the  glottis. 

HYOLDEUS  PAEVUS. 
(Kerato-hyoideics  Parvus.) 

Situated  above  and  before  the  preceding  muscle,  it  is  small» 
flat,  and  triangular. 

Origin. — From  the  inferior  border  of  the  anterior  extremity 
of  the  comu,  and  the  posterior  border  of  the  comiculum. 

Insertion. — To  the  body  and  heel  process  of  the  os  hyoides, 
filling  up  the  space  between  the  three  bones. 

Relation. — Externally  with  the  hyo-glossus  and  the  lingual 
arteries ;  internally  with  the  mucous  membrane. 

Action. — It  approximates  the  three  bones  to  which  it  is 
attached. 

HYOIDEUS  TRANSVERSUS. 

A  short,  thin  muscle,  joining  the  comicula  together  by  their 
superior  extremities,  which  on  contraction  it  approximates. 

STYLO-HYOIDEUS. 
(Fig.  71./.) 

Flat  and  triangular,  it  fills  up  the  space  between  the  posterior 
part  of  the  angle  of  the  comu,  and  the  styloid  process  of  the 
occipital  bone. 

Origin. — The  anterior  border  of  the  styloid  process. 

Insertion. — The  posterior  part  of  the  comu. 

Relation. — Externally  with  the  parotid  gland,  and  internally 
with  the  guttural  pouch.  Its  posterior  fibres  blend  with  those  of 
the  origin  of  the  digastricus. 

Action. — It  draws  back  and  depresses  the  os  hyoides. 


palpebral  group.  173 

Palpebral  Group, 

The  palpebral,  or  muscles  of  the  eyelids  are  four  in  number, 
named  as  follows  : — 

Orbicularis  palpebrarum. 

Lacbrymalis. 

Levator  palpebrse  superioris  externus. 

Levator  palpebrse  superioris  internus. 


ORBICULARIS  PALPEBRARUM. 

{Musculus  Ciliaris.) 
(PL.  II.  5.    Fig.  70.  //.) 

A  large,  thin,  oval  sphincter,  common  to  the  upper  and  lower 
eyelids,  and  situated  around  them. 

Attachments. — It  is  covered  by  the  skin,  to  which  it  inti- 
mately adheres.  The  superior  portion  is  the  larger,  and  consists 
of  numerous  fleshy  fasciculi,  with  a  small  flat  tendon  which 
is  attached  to  the  lachrymal  tubercle,  near  the  nasal  angle 
of  the  eye. 

Action.- — It  closes  the  eyelids. 

LACHRYMALIS. 

{Lachrymo-LabiaUs.) 

A  very  thin  muscle  placed  below  and  before  the  orbit,  con- 
tinuous with  the  levator  labii  superioris  in  front,  the  panniculus 
behindj  and  the  orbicularis  palpebrarum  above.  It  becomes 
blended  with  the  buccinator. 

LEVATOR  PALPEBRiE  SUPERIORIS   EXTERNUS. 

(Fronto-superciliaris.) 

(Fig.  70.  e.) 

Situated  immediately  above  the  orbit,  it  is  subcutaneous,  short, 
thin,  and  narrow. 

Attachments. — It  arises  from  the  external  surface  of  the 
frontal  bone,  near  the  supra- orbital  foramen.  The  fibres  pass 
downwards  and  outwards,  blending  with  the  orbicularis  at  the 
superior  part  of  the  lid,  towards  the  inner  angle  of  the  eye. 


174  MYOLOGY. 

Relation. — Externally  with  the  skin;  internally  with  th& 
bone. 

Action. — It  corrugates  the  skin  of  the  upper  eyelid,  but  is 
scarcely  a  levator, 

LEVATOR  PALPEBR^  SUPERIORIS  INTERNUS. 
(Orbito-palpebralis. ) 

Situated  within  the  orbital  fossa,  in  relation  with  the  superior 
straight  tnuscle  of  the  eyeball,  this  muscle  is  narrow,  thin,  and 
band-like. 

Origin. — From  the  superior  border  of  the  optic  foramen,  on  a 
level  with  the  lachrymal  gland,  passing  under  which  it  becomes 
aponeurotic,  running  between  the  conjunctiva  and  the  fibrous 
portion  of  the  upper  lid. 

Insertion. — To  the  inner  surface  of  the  lid,  and  the  tarsal 
cartilage. 

Action. — It  raises  the  upper  eyelid. 

Auricular  Group. 

The  external  muscles  of  the  ear  consist  of  an  extrinsic  and  an 
intrinsic  group.  The  extrinsic  muscles,  eight  in  number,  are  as 
follows : — 

AttoUens  maximus.  Ketrahens  externus. 

AttoUens  anticus.  Retrahens  medius. 

AttoUens  posticus.  Retrahens  internus. 

Abducens. 

Mastoido-auricularis. 

ATTOLLENS  MAXIMUS. 

(Temporo-auricularis  Externus. ) 

(PL.  IL  2'.. 

Situated  immediately  under  the  skin,  above  the  temporal 
muscle,  and  in  front  of  the  inner  side  of  the  ear,  it  is  broad, 
thin,  and  fleshy. 

Origin. — From  the  whole  of  the  parietal  crest,  joining  its 
fellow  in  the  mesian  line  posteriorly. 

Insertion. — To  the  scutiform  cartilage,  sending  a  small  band 
to  the  internal  border  of  the  base  of  the  conchal  cartilage. 


AURICULAR   GROUP. 


175 


Relation. — Externally  with  the  skin;  internally  with  the 
temporalis  and  attoUens  posticus ;  posteriorly  with  the  retrahens 
externus. 

Action. — It  adducts  and  elevates  the  ear,  and  also  turns  its 
opening  forwards. 

ATTOLLENS  ANTICUS. 

{^Zygomatico-auricularis. ) 

(PL.  II.  2".) 

Subcutaneous,  and  in  front  of  the  ear,  this  muscle  is  small 
and  thin,  consisting  generally  of  two  fleshy  bundles,  joined  by 
condensed  cellular  tissue. 


^^y^^W^^. 


Fig.  72. 

Muscles  of  the  external  ear  —  posterior  view,  a.  Inferior,  and  6, 
superior  layer  of  the  scuto-auricularis  internus ;  c,  AttoUens  posticus ; 
d,  Retrahens  externus;  e,  Ketrahens  medius ;  /,  Retrahens  internus; 
g,  Mastoido-aiiricularis. 

Origin. — From  the  superior  part  of  the  temporal  zygomatic 
process  by  a  flat  tendon,  which  blends  in  front  with  the  orbicu- 
laris palpebrarum. 

Insertion. — By  two  sets  of  fibres — one  to  the  anterior  part 
of  the  scutiform,  the  other  to  base  of  the  conchal  cartilage, 
blending  with  the  scuto-auricularis  externus  and  the  abducens. 

Relation. — Externally  with  the  skin ;  internally  with  the 
temporal  muscle  ;    posteriorly  with  the  parotid  gland. 

Action. — It  draws  the  ear  forwards. 


176  MYOLOGY. 

ATTOLLENS  POSTICUS. 

(Temporo-auricularis  Internua.) 

(Fig.  72.  c.) 

This  is  a  triangular  muscle  of  a  bright-red  colour,  situated 
under  the  attollens  maxiraus. 

Origin. — From  the  parietal  crest,  and  by  cellular  tissue  from 
the  temporalis. 

Insertion. — The  tendon  is  directed  obliquely  round  the  inter- 
nal face  of  the  concha,  terminating  in  the  conchal  cartilage,  below 
the  insertion  of  the  retrahens  externus. 

Relation. — Externally  with  the  maximus ;  internally  with  the 
temporalis. 

Action. — It  elevates  and  adducts  the  ear. 

RETEAHENS  EXTERNUS. 

(Cervico-auricularis  Externus.) 

(Fig.  72.  d.) 

Situated  on  the  poll,  at  the  side  of  the  ear,  it  is  thin  and  flat, 
joining  the  attollens  maximus. 

Origin. — From  the  cordiform  portion  of  the  ligamentum 
nuchse. 

Insertion. — To  the  middle  of  the  posterior  surface  of  the 
conchal  cartilage. 

Relation. — Externally  with  the  skin  ;  internally  with  the 
retrahens  internus  and  medius. 

Action. — It  draws  the  ear  backwards  and  downwards. 

RETRAHENS  MEDIUS. 

(Cervico-auricularis  Medius.) 

(Fig.  72.  e.) 

Broad  and  thin ;  situated  below  the  preceding. 

Origin. — The  same  as  the  externus. 

InseHion. — To  the  external  part  of  the  base  of  the  concha 
under  the  abducens,  its  tendon  passing  over  the  superior  portion 
of  the  parotid  gland. 

Relation. — Externally  with  the  preceding  muscle ;  internally 
with  the  internus  aud  the  parotid  gland. 

Action. — It  rotates  the  ear,  turning  the  opening  backwards. 


AURICULAR  GROUP.  177 

RETRAHENS  INTERNUS, 

{Cervico-auricularis'  Inter  nus. ) 

(FiQ.  72./.) 

Thin,  fleshy,  and  situated  below  the  preceding  muscle. 
Origin. — The  same  as  the  two  last  named. 
Insertion. — To   the   dilated  lower   part  of  the   conchal   car- 
tilage. 

Relation. — Externally  with  the  medius  and  the  parotid  gland. 
Action. — It  assists  the  medius. 


MASTOIDO-AURICULARIS. 

(Fig.  72.  g.) 

Situated  deeply,  at  the  base  and  inner  side  of  the  concha, -this 
muscle  is  very  small,  flat,  and  slender. 

Origin. — From  the  external  auditory  meatus 

Insertion. — To  the  base  of  the  concha. 

Action. — It  draws  the  concha  downwards,  and  thus  shortens 
Ae  external  ear. 

ABDUCENS. 

{Deprimens  Aurem — Parotido-auricularis.) 

{Pl.  II.  1.     Fig,  70.  a.) 

Situated  below  the  root  of  the  ear,  and  on  the  outer  side  of 
the  parotid  gland,  it  is  flat  and  thin  below,  narrower  and 
thicker  above. 

Origin. — From  tbe  external  surface  of  the  parotid  gland. 

Insertion. — To  the  external  part  of  the  base  of  the  concha. 

Relation. — Externally  with  a  thin  aponeurotic  portion  of  the 
panniculus ;   internally  with  the  parotid  gland. 

Action. — It  draws  the  ear  downwards  and  outwards. 

INTRINSIC    MUSCLES. 

The  intrinsic  muscles  of  the  external  ear  are  the  scuto-auri- 
cularis.  externus  and  internus. 


178  MYOLOGY. 

SCUTO-AURICULA.EIS    EXTEENUS. 
(Fig.  70.  b.  c.  d.) 

Origin. — From  the  external  surface  of  the  scutiform  car- 
tilage. 

Insertion. — To  the  inner  side  of  the  conchal  cartilage.  It  is 
composed  of  three  bundles,  covered  by  the  attollens  maximus, 
and  it  assists  that  muscle  to  turn  the  openiog  of  the  ear  forwards. 

SCUTO-AURICULARIS    INTEHNUS. 
(Fig.  72.  a.  b.) 

It  consists  of  two  pale  bundles  which  cross  each  other. 

Origin. — The  under  surface  of  the  scutiform  cartilage,  the 
•fibres  being  directed  backwards. 

Insertion. — The  posterior  portion  of  the  base  of  the  concha. 

Action. — It  turns  the  opening  of  the  ear  outwards  and  back- 
ivwards,  thus  antagonising  the  externus. 

Muscles  of  the  Trunk. 

This  large  division  includes  the  rest  of  the  muscles,  excepting 
those  which  more  especially  belong  to  the  limbs.  We  shall  divide 
the  trunk  into  the  following  regions,  thus  indicating  the  groups 
,into  which  the  muscles  most  naturally  fall  : — 

Diaphragmatic. 
Dorso-lumbar. 
Sublumbar. 
Coccygeal. 

Cervical  Kegion. 


Cervical. 
Pectoral. 
Costal 
Abdominal. 


The  muscles  of  the  neck  may  be  said  to  consist  of  an  inferior 
and  two  lateral  groups,  the  latter  lying  on  each  side  of  the  central 
division  formed  by  the  vertebrae  and  the  ligamentum  nuchse,  and 
the  former  being  situated  underneath  the  vertebrae. 

Inferior  Cervical  Group. 

The  following  muscles,  eight  in  number,  may  be  placed  in  this 
group  : 


INFERIOR   CERVICAL   GROUA  179 


Sterno-maxillaris, 
Stemo-thyro-hyoideus. 
Subscapulo-h  yoideus. 
Rectus  capitus  anticus  major. 


Rectus  capitis  anticus  minor. 
Rectus  capitus  lateralis. 
Scalenus. 
Longus  colli. 


STERNO-MAXILLARIS. 
(Pl.  IL  20.) 

Placed  along  the  lower  border  of  the  levator  humeri,  this  muscle 
is  long,  narrow,  and  flat,  its  fibres  extending  forwards  and 
upwards  ;  it  is  fleshy,  terminating  in  a  flat  tendon. 

Origin. — From  the  anterior  portion  of  the  cariniform  cartilage: 
it  is  united  to  its  fellow  along  its  inferior  third. 

Insertion. — To  the  angle  of  the  lower  jaw. 

Relation. — Externally  with  the  panniculus  and  the  parotid 
gland  ;  internally  with  the  sterno-thyro-hyoideus  and  subscapulo- 
hyoideus,  the  trachea  and  carotid  artery ;  the  jugular  vein  runs 
along  its  superior  border. 

Action. — Acting  with  its  fellow,  it  flexes  the  head  downwards, 
or  singly,  it  turns  the  head  to  one  side. 


STERNO-THYRO-HYOIDEUS. 

(Sterno-thyroideus  and  Sterno-hyoideus.) 

(Pl.  IIL  3.) 

This  is  a  slender  muscle  situated  in  front  of  the  trachea ;  it  is 
narrow,  ribbon-shaped,  and  divided  into  two  parts.  Fleshy  at  its 
origin,  it  divides  half  way  up  the  neck  into  two  portions,  each 
having  a  tendon  of  insertion.  About  their  middle  the  sterno- 
thyro-hyodei  have  tendinous  intersections,  which  render  tl^em 
more  or  less  digastric. 

Origin. — From  the  superior  part  of  the  cariniform  cartilage, 
intimately  blended  with  its  fellow. 

Insertion. — By  one  tendon,  to  the  postero-inferior  part  of  the 
thyroid  cartilage,  and  by  the  other  to  the  spur  process  of  the  os 
hyoides. 

Relation. — Inferiprly  with  the  sterno-maxillaris ;  superiorly 
with  the  trachea. 

Action. — It  depresses  the  hyoid  bone,  and  with  it  the  larynx 
and  base  of  the  tongue. 


180  *  MYOLOGY. 

SUBSCAPULO-HYOIDEUS. 
(PL.  n.  23.) 

More  laterally  situated  than  the  last,  this  muscle  is  broad, 
thin,  and  elongated,  its  fibres  extending  forwards  and  upwards. 
Aponeurotic  at  its  origin,  it  is  followed  by  a  long,  flat,  fleshy 
belly,  ending', in  a  flat  tendon,  which  joins  that  of  the  stemo- 
hyoideus. 

OHgin. — From  the  fascia  covering  the  subscapularis  muscle. 

Insertion. — To  the  inferior  border  of  the  spur  process  of  the 
OS  hyoides. 

Relation. — Externally  with  the  subscapularis,  pectoralis  parvus, 
and  sterno-m axillaris,  blending  also  with  the  levator  humeri; 
internally  with  the  muscles  on  the  inner  aspect  of  the  shoulder, 
the  scalenus  and  rectus  capitis  anticus  major,  the  trachea  and  the 
carotid  sheath. 

Action. — It  depresses  the  hyoid  apparatus. 


RECTUS    CAPITIS    ANTICUS    MAJOR. 

( Trachelo-suhoccipitalis. ) 

(PL.  III.  2.) 

This  is  the  long  flexor  of  the  head,  and  is  situated  along  the 
anterior  half  of  the  region.  It  is  long,  and  has  a  flattened,  fleshy 
belly,  converging  from  two  or  three  slips  of  origin,  and  teiminat- 
ing  anteriorly  in  a  conical  tendon. 

Origin. — Posteriorly,  from  the  transverse  processes  of  the 
third,  fourth,  and  fifth  cervical  vertebrsB. 

Insertion. — To  the  basilar  process  of  the  occipital  and  body  of 
the  sphenoid  bone. 

Relation. — Externally  with  the  levator  humeri,  and  subscapulo- 
hyoideus ;  internally  witb  its  fellow  and  the  longus  colli  ; 
anteriorly  with  the  gutteral  pouch  and  carotid  artery,  and 
superiorly  with  the  occipito-atloid  joint,  and  rectus  capitis, 
anticus  minor. 

Action. With  its  fellow  it  flexes  the  head  downwards ;  when 

acting  singly,  it  flexes  it  laterally. 


INFERIOR   CERVICAL   GROUP. 


181 


RECTUS   CAPITIS   ANTICUS   MINOR. 

(Atloido-suboccipitalis. ) 

(Fia.  75.  c.) 

This,  the  short  flexor  of  the  head,  is  situated  on  the  inner  and 

upper  side  of  the  preceding  muscle,  and  is  short,  slender,  and 

almost  entirely  fleshy. 

Origin . — Posteriorly,  from  the  lower  part  of  the  body  of  the 
atlas. 

Insertion. — To  the  basilar  process  of  the  occipital,  and  body 
of  the  sphenoid  bone,  by  the  preceding  muscle. 

Relation. — Infero-externally  with  the  rectus  major  ;  supe- 
riorly with  the  capsular  ligament  of  the  occipito-atloid  articu- 
lation. 

A.ction. — It  assists  in  flexing  the  head. 


RECTUS   CAPITIS   LATERALIS. 
{A  tloido-styloideus.) 
(Fig.  75.  6.) 
This  muscle,  still  smaller  than  the  last  and  like  it  in  structure, 
is  placed  rather  more  externally. 

Origin. — From  the  inferior  part  of  the  ring  of  the  atlas,  on 
the  outer  side  of  the  rectus  minor. 

Insertion. — To  the  styloid  process  of  the  occipital  bone. 
Relation. — Inferiorly  with  the  rectus  major  ;  superiorly  with 
the  capsular  ligament  of  the  occipito-atloid  articulation  ;  exter- 
nally with  the  parotid  gland. 

Action. — It  assists  the  preceding  muscles. 


SCALENUS. 

(  Costo-cervicalis. ) 

(PL.  IIL  6.) 

Situated  at  the  postero-inferior  part  of  the  region,  at  the  side 
of  the  anterior  aperture  of  the  thoracic  cavity,  the  scalenus  is 
triangular  in  shape,  and  divided  into  a  superior  or  posterior,  and 
an  inferior  or  anterior  portion ;  the  fibres  run  forwards  and 
upwards,  and  form  several  fleshy  masses,  with  strong  tendinous 


182  MYOLOGY. 

intersections.  The  anterior  portion  is  the  larger,  flat  from  side 
to  side,  and  thin  in  front. 

Origin  of  the  Anterior  Portion. — From  the  transverse  pro- 
cesses of  the  last  four  cervical  vertebra  by  short  fleshy  fasciculi. 

Insertion. — The  anterior  and  outer  border  of  the  first  rib. 

Origin  of  the  Posterior  Portion. — From  the  transverse  pro- 
cesses of  the  last  three  or  four  cervical  vertebrae. 

Insertion. — To  the  superior  part  of  the  first  rib. 

Relation. — Superiorly  with  the  intertransversalis  colli;  inferiorly 
with  the  sterno-maxillaris  ;  externally  with  the  levator  humeri, 
pectoralis  parvus,  and  subscapulo-hyoideus  ;  internally  with  the 
trachea  and  carotid  artery,  and  on  the  left  side  with  the  oesopha- 
gus. Across  its  inferior  border  runs  the  jugular  vein,  and 
between  its  anterior  and  posterior  portions  pass  the  nerves  of  the 
brachial  plexus. 

Action. — When  the  first  rib  is  fixed,  together  these  muscles 
extend  the  neck ;  acting  singly,  each  turns  it  to  one  side.  When 
the  neck  is  fixed,  by  drawing  the  first  rib  forward  and  supporting 
it,  it  acts  as  an  inspiratory  muscle. 


LONGUS    COLLI. 

(Subdorso-atloidevs.) 

(Fig.  75.  a.) 

In  the  horse  this  is  a  single  muscle,  situated  under  the  centra 
of  the  cervical  and  anterior  dorsal  vertebrae.  The  dorsal  portion 
is  fleshy,  the  cervical  being  made  up  of  smaller  fasciculi,  con- 
voluted and  intersected  by  tendinous  fibres.  The  fasciculi  run 
inwards  and  forwards. 

Origin. — From  the  inferior  surface  of  the  centra  of  ther  first 
six  dorsal,  and  the  inferior  spines  and  transverse  processes  of  the 
six  posterior  cervical  vertebrae. 

Insertion. — By  a  strong  tendon  to  the  inferior  spine  or 
tubercle  of  the  atlas  ;  it  is  also  strongly  attached  to  the  second 
cervical  segment. 

Relation. — Externally  and  anteriorly  with  the  rectus  capitis 
anticus   major ;    externally    and   posteriorly  with   the  scalenus ; 
inferiorly  with  the  trachea,  oesophagus,  blood-vessels,  and  nerves  ; 
superiorly  with  the  vertebroB.      The  dorsal  portion  is  related  with  v 
the  pleura  and  sympathetic  nerves. 


LATEBAL    CEEVICAL    GROUT,  183 

Action. — It  flexes  the  neck  downwards,  and  moves  one  vertebra 
on  another. 

Lateral  Ceevical  Group. 

This  is  a  numerous  group,  but  one  difficult  of  satisfactory  suo- 
division.  The  following  Table  enumerates  the  muscles  in  the 
order  in  which  they  may  be  conveniently  demonstrated  : — 


Levator  humeri. 
Trapezius  cervicalis. 
Rhomboideus  longus. 
Serratus  magnus  (a  portion). 
Splenius 

Trachelo-mastoideus. 
Complexus  major. 


Complexus  minor. 
Rectus  capitis  posticus  major. 
Rectus  capitis  posticus  minor. 
Obliquus  capitis  anticus. 
ObUquus  capitis  posticus. 
Spinalis  colli. 
Litertransversalis  colli. 


LEVATOR    HUMERI. 

(Mastoido-humeralis.) 

(Pl.  IL  12.) 

Occupying  the  infero-lateral  part  of  the  neck,  this  muscle  is 
large,  flat,  and  elongated,  extending  downwards  from,  the  back  of 
the  head  to  the  arm.  Its  fleshy  portion  is  divisible  into  deep 
and  superficial  parts,  the  first  being  placed  anteriorly. 

Attachments. — Anteriorly,  by  one  tendon  to  the  crest  of  the 
occiput  and  the  mastoid  process  of  the  temporal  bone  ;  by  the 
other  to  the  wing  of  the  atlas,  this  tendon  being  also  common  to 
the  splenius  and  trachelo-ma,stoideus  ;  to  the  transverse  processes 
of  the  second,  third,  and  fourth  cervical  vertebrse,  and  the  fascia 
of  the  neck.  Covering  the  shoulder  joint,  it  is  attached  to  a  line 
extending  downwards  from  the  deltoid  ridge ;  and  to  the  fascia  of 
the  muscles  of  the  shoulder  and  arm,  joining  the  scapular  fascia 
by  an  aponeurotic  expansion  continuous  also  with  the  fascia  of  the 
cervical  trapezius. 

Relation. — Externally  with  the  panniculus ;  inferiorly  with 
the  carotid  artery,  jugular  vein,  and  stemo-maxillaris  ;  internally 
with  the  splenius,  trachelo-mastoideus,  rectus  capitis  anticus  major, 
scalenus,  serratus  magnus,  and  other  muscles  ;  anteriorly  with  the 
parotid  gland.  It  is  connected  with  the  ligamentum  nuchas  by 
the  aponeurosis  of  the  panniculus,   and  infero-laterally  becomes 


184  MTOLOGY. 

blended  with  that  muscle ;  hence  it  may  be  said  to  have  an. 
indirect  sternal  attachment. 

Action. — When  the  head  is  fixed,  it  advances  the  entire  limbj 
if  the  limbs  are  fixed,  it  aids  in  turning  the  head  and  neck  to- 
one  side,  or  with  its  fellow  in  depressing  them. 


TRAPEZIUS  CERVICALIS. 

(Cervico-acromialis.) 

(PL.  n.  13.) 

Situated  supero-posteriorly,  this,  the  cervical  portion  of  the- 
trapezius  muscle,  is  thin,  flat,  and  triangular,  its  fibres  converging 
downwards  and  backwards.  It  is  aponeurotic  above,  and  poste- 
riorly, where  it  joins  the  dorsal  portion. 

Origin. — ^From  the  funicular  portion  of  the  ligamentum  nuchas. 

iTisertion. — With  the  dorsal  trapezius  to  the  spine  of  the 
scapula,  at  its  tubercle,  and  to  the  scapular  fescia. 

Relation. — Externally  with  fascia  from  the  levator  humeri  and 
panniculus  ;  internally  with  the  splenius,  serratus  magnus,  rhom- 
boideus  longus,  pectoralis  parvus,  and  antea  spinatus. 

Action. — It  elevates,  and  draws  the  shoulder  forwards. 


RHOMBOIDEUS  LONGUS. 

(Cervico-subscapularis. ) 
(PL.  III.  9.) 

It  is  placed  on  the  supero-lateral  part  of  the  neck,  just  below 
the  cordiform  portion  of  the  ligamentum  nuchaB.  It  appears  as  a 
tapering  triangle,  widest  posteriorly,  and  very  fleshy  in  its 
structure. 

Origin. — From  the  funicular  portion  of  the  ligamentum  nuchae, 
as  high  as  the  second  cervical  vertebra 

Insertion. — To  the  inner  surface  of  the  anterior  angle  of  the 
scapula,  and  to  its  cartilage  of  prolongation,  just  above  the 
serratus  magDus. 

Relation. — Externally  with  the  cervical  trapezius  ;  inferiorly 
with  the  splenius ;  posteriorly  with  the  rhomboideus  brevis,  with 
which  it  blends  ;  internally  with  the  ligamentum  nuchse. 

Action. — To  elevate  and  draw  the  scapula  forwards. 


LATERAL    CERVICAL   GROUP.  185 

SERRATUS  MAGNUS. 
(PL.  HL  10.) 

The  cervical  portion  of  the  serratus  magnus  will  be  described 
-with  the  costal  portion.     (See  costal  region.) 

SPLENIUS. 

{Cervico-mastoideus. ) 

(PL.  III.  7.) 

This  is  a  large  muscle  included  between  the  funicular  part  of 
the  Ugamentum  nuchse,  and  the  vertebrae  below.     It  is  broad. 


Fig.  73. 
Lateral  cervical  muscles-deep  layer,    a,  Complexus  major;  6,  Trachelo-mastoideus  ; 
eccc,  Intertransversalis  eolH- 

liat,  and  triangular ;  aponeurotic  only  at  its  periphery,  its  belly  is 
made  up  of  large  fleshy  bundles,  which  are  directed  obliquely 
forwards  and  upwards  to  the  head  and  first  cervical  vertebra. 

Attachments.—To  the  funicular  portion  of  the  ligamentum 
nuchse,  the  transverse  processes  of  the  third,  fourth,  and  fifth 
cervical,  and  the  spines  of  the  first  four  or  five  dorsal  vertebrae ; 
to  the  crest  and  mastoid  ridge,  in  union  with  the  tendon  of  the 
trachelo-mastoideus,  and  to  the  wing  of  the  atlas,  aloug  with  the 
common  tendon  of  the  trachelo-mastoideus  and  the  levator  humeri. 


186  MYOLOGY. 

Relation. — Externally  with  the  levator  humeri,  cervical  trape- 
zius, serratus  magnus,  and  rhomboideus  muscles;  internally  with 
the  complexus  major,  trachelo-mastoideus,  and  obliquus  capitis 
muscles. 

Action. — With  its  fellow  it  elevates  the  head;  alone  it  draws 
the  head  to  one  side. 

TRACHELO-MASTOIDEUS.* 

(Dorso-mastoideus. ) 

(Fig.  73.  ft.) 

Situated  under  and  along  tbe  inferior  border  of  the  splenius, 
it  is  elongated  and  flesby,  its  fibres  passing  forwards  and 
upwards ;  the  belly  is  divided  into  two  portions,  which  run 
parallel,  each  terminating  by  a  tendon  anteriorly. 

Origin. — From  the  transverse  processes  of  the  first  two  dorsal 
and  the  oblique  processes  of  the  last  five  cervical  vertebraB. 

Insertion. — By  two  tendons ;  one  to  the  wing  of  the  atlas, 
common  also  to  the  splenius  and  levator  humeri ;  the  other, 
continuous  with  that  of  the  splenius,  to  the  mastoid  ridge. 

Relation. — Externally  with  the  splenius  ;  internally  with  the 
spinalis  colli ;   posteriorly  with  the  longissimus  and  spinalis  dorsi. 

Action. — With  its  fellow  to  erect  the  head ;  acting  alone,  it 
draws  it  to  one  side. 

COMPLEXUS  MAJOR. 

(Dorso-occipitalis. ) 

(Fig.  73.  a.) 

Situated  on  the  inside  of  the  splenius,  this  muscle  resembles 
an  elongated  triangle,  with  the  base  backwards  ;  it  is  fleshy,  with 
tendinous  intersections.  The  posterior  part  is  aponeurotic  at  its 
origin,  the  anterior  terminating  in  a  single  tendon. 

Origin. — From  the  transverse  and  spinous  processes  of  the 
first  five  dorsal,  and  the  oblique  processes  of  all  the  cervical 
vertebrae. 

Insertion. — To  the  side  of  the  occipital  tuberosity. 

Relation.  —  Externally  with  the  splenius  and  trachelo-* 
mastoideus ;  internally  with  the  complexus  minor,  ligamentum 
nuchse,  and   oblique  muscles ;  posteriorly  with   the   longissimus 

*  This  is  the  complexus  minor  of  M.  Chauveau. 


LATERAL    CERVICAL    GROUP.  187 

and  spinalis  dorsi.      The  superior  cervical  artery  passes  through 
its  divisions  posteriorly. 

Action. — It  extends  the  head. 

COMPLEXUS  MINOR. 

(Axoido-occipitalis  Longus.) 

(Fig.  74.  c.) 

Situated  on  the  poll,  it  is  fusiform,  slender,  and  fleshy,  being 
tendinous  at  its  insertion. 

Origin. — From  the  neural  spine  of  the  dentata. 

Insertion. — With  the  tendon  of  the  complexus  major. 

Relation. — Externally  with  the  complexus  major;  inferiorly 
with  the  rectus  capitis  posticus  major;  internally  with  the  liga- 
mentum  nuchse. 

Action. — To  assist  the  complexus  major. 

RECTUS   CAPITIS   POSTICUS  MAJOR. 
(Axoido-occipitalis  Brevis.) 
(Fig.  74.  d.) 

Situated  below  the  complexus  minor,  it  is  long,  slender,  and 
fusiform. 

Origin. — From  the  neural  spine  of  the  dentata. 

Insertion. — To  a  roughened  depression  on  the  occiput  below 
its  tubercle. 

Relation. — Externally  with  the  complexus  major ;  inferiorly 
with  the  rectus  capitis  posticus  minor. 

Action. — To  extend  the  head. 

RECTUS   CAPITIS   POSTICUS   MINOR. 

(Atloido-occipitalis  Brevis.) 

(Fig.  74.  e.) 

Situated  below  the  preceding,  this  muscle  is  small,  flat,  and 
somewhat  triangular. 

Origin. — From  the  supero-anterior  part  of  the  atlas. 

Insertion. — Below  that  of  the  preceding  muscle. 

Relation. — Superiorly  with  the  major ;  inferiorly  with  the 
capsular  ligament  ;  externally  with  the  obliquus  capitis  anticus ; 
internally  with  the  ligamentum  nuchas. 

Action. — It  assists  the  preceding  muscle. 


188 


MYOLOGY. 


OBLIQUUS   CAPITIS    ANTICUS. 

(Atloido-mastoideus.) 

(Fig.  74.  b.) 

Situated  on  the  side  of  the  poll,  it  is  flat,  nearly  square,  and' 
■fleshy,  with  tendinous  intersections. 

Origin. — From  the  supero-anterior  portion  c^  the  roughened 
edge  of  the  wing  of  the  atlas. 

Insertion. — To  the  mastoid  crest  and  styloid  process  of  the 
occiput. 


Occipito-atlo-axoid  muscles— lateral  view,  a,  Obliqnus  capitis  posticus  ;  b,  Obliqnus 
capitis  anticus;  c,  Complexus  minor  ;  d,  Rectus  capitis  posticus  major;  e,  Eectus 
capitis  posticus  minor. 

Relation. — Externally  with  the  tendon  of  the  splenius ; 
internally  with  the  caosular  ligament  and  rectus  capitis  posticus 
muscles. 

Action. — Together,  to  extend  the  head  slightly;  singly,  to 
bend  it  laterally  on  the  atlas. 


OBLIQUUS    CAPITIS   POSTICUS. 

{Axoido-atloideus.) 

(Fig.  74.  a.) 

Situated  between  and  upon  the  atlas  and  axis,  it  is  broad,  flat, 
thick,  and  fleshy. 


LATERAL    CERVICAL    GROUP.  189 

Origin. — From  the  lateral  surface  and  superior  spine  of  the 
dentata,  and  the  capsular  ligament. 

Insertion. — To  the  upper  surface  of  the  wing  and  body  of  the 
atlas. 

Relation. — Externally  with  the  splenius,  trachelo-mastoideus, 
and  complexus  major  ;  internally  with  the  atlas,  axis,  and  the  atlo- 
axoid  capsular  ligament ;  superiorly  with  the  rectus  posticus,  and 
inferiorly  with  the  rectus  anticus  major  muscles. 

Action. — It  is  the  rotator  muscle  of  the  head. 


SPINALIS   COLLL 
{Dorso-spinalis. ) 

Deep-seated  on  the  side  of  the  neck,  it  consists  of  six  short 
fleshy  bundles,  intersected  by  tendons,  whose  fibres  extend 
obliquely  upwards  and  inwards. 

Origin. — Posteriorly,  from  the  oblique  processes  of  the  first 
dorsal  and  the  last  five  cervical  vertebrae. 

Insertion. — To  the  neural  spines  of  all  the  cervical  vertebrae 
but  the  first. 

Relation. — ^Externally  with  the  complexus  major  and  trachelo- 
mastoideus  ;  internally  with  the  ligamentum  nuchae  and  the 
vertebrae. 

Action. — To  extend  and  curve  the  neck. 


Intertransversalis  Colli. 

(Intercervicalis. ) 
(Fig.  73.  c  c  c  c.) 

Placed  along  the  lateral  part  of  the  cervical  vertebrae,  it 
■consists  of  six  distinct  bundles  with  strong  tendinous  intersections, 
the  fibres  passing  obliquely  outwards  and  upwards. 

Origin. — The  oblique  process  of  one  vertebra. 

Insertion. — The  transverse  process  of  the  vertebra  in  front, 
filling  up  the  interspaces  of  all,  excepting  those  of  the  first  and 
second. 

Relation. — With  several  deep-seated  muscles  of  the  neck,  the 
vertebrae,  the  vertebral  artery,  and  vein. 

Action. — To  assist  in  flexing  the  neck  laterally. 


190  MYOLOGY, 


Costal  Region. 


The  muscles  of  this  region  are  those  which  cover  the  lateral 
aspect  of  the  thoracic  cavity ;  some  of  them  are  attached  to  the 
anterior  limb,  three  of  which  we  describe  the  first,  as  it  is 
necessary  in  dissection  to  cut  through  them,  -and  remove  or 
deflect  the  limb  in  order  to  expose  fully  the  deeper-seated 
muscles.      The  following  are  the  muscles  of  the  region  : — 


Trapezius  dorsalis. 
Rhomboidfius  brevis. 
Lafcissimus  dorsi. 
Serratus  magnus. 


Superficialis  costaruni. 
Transversalis  costarum. 
Levatores  costarum. 
Intercostal  es. 


TRAPEZIUS   DORSALIS. 

{Dorso-acromialis.) 

(Pl.  IL  14.) 

Situated  on  the  side  of  the  withers,  this  muscle  is  flat  and 
triangular,  being  almost  the  reversed  counterpart  of  the  cervical 
trapezius.  The  two  form  the  trapezius  muscle.  It  is  aponeu- 
rotic at  its  superior  border,  while  its  belly  is  fleshy,  terminating; 
la  a  flat  tendpn. 

Origin. — Superiorly,  from  the  supraspinous  ligament,  and 
from  the  third  dorsal  spine  back  to  the  tenth  or  eleventh.  The 
fibres  converge  downwards  and  forwards,  over  the  superior  costa. 
of  the  scapula,  and  join  the  cervical  portion. 

Insertion. — The  tubercle  on  the  spine  of  the  scapula. 

Relation. — Externally  with  the  skin  and  panniculus;  internally 
with  the  rhomboideus  brevis,  postea-spinatus,  and  latissimus. 
dorsi. 

Action. — To  draw  upwards  and  retract  the  scapula. 

KHOMBOIDEUS   BREVIS. 

(Dorso-subscapularis.) 

(Pl,  in,  12,) 

Deep-seated,  on  the  side  of  the  withers  above  the  scapula,  it 
is  flat  and  square ;  the  fibres  extend  downwards,  and  are  entirely 


COSTAL    EEGION.  191 

Origin. — From  the  neural  spines  of  the  first  four  or  five 
dorsal  vertebrae,  and  from  their  supraspinous  ligament. 

Insertion. — To  the  inner  surface  of  the  superior  costa  of  the 
scapula,  and  to  its  cartilage  of  prolongation. 

Relation. — Externally  with  the  cartilage  of  the  scapula,  and 
the  dorsal  trapezius,  and  separated  from  the  anterior  portion  of 
the  superficialis  costarum  by  a  thin  layer  of  elastic  tissue ; 
anteriorly  with  the  rhomboideus  longus  ;  posteriorly  with  the 
latissimus  dorsi;   internally  with  the  splenius. 

Action. — To  draw  the  scapula  upwards. 

LATISSIMUS    DORSI 

(  Dorso-humeralis. ) 

(PL.  IL  15.) 

This  muscle  is  situated  on  the  supero-lateral  part  of  the  chest 
and  the  loins ;  it  is  very  large,  flat,  thick,  and  triangular,  its 
fibres  extending  obliquely  downwards  and  forwards  ;  it  is  aponeu- 
rotic above,  fleshy  below,  with  a  tendinous  and  aponeurotic 
insertion. 

Origin. — By  a  broad  aponeurosis,  from  the  supraspinous  liga- 
ment and  spinous  processes  of  the  vertebrae,  commencing  about 
the  highest  point  of  the  withers,  and  stretching  as  far  as  the  last 
lumbar.  The  fleshy  portion  becomes  thick  just  behind  the 
scapula,  then  it  contracts,  terminating  in  a  flat  tendon,  which 
passes  under  the  latter.  It  fits  in  a  notch  at  the  dorsal  scapular 
angle,  formed  by  the  projection  of  the  cartilage  of  prolongation, 
which  it  overlaps. 

Insertion. — The  internal  tuberosity  of  the  humerus,  along 
with  the  teres  internus,  and  between  the  two  insertions  of  the 
coraco-humeralis.  Before  passing  under  the  scapula,  it  gives  oflf 
a  strong  aponeurosis,  which  passes  over  the  supero-posterior  part 
of  the  scapula,  and  becomes  continuous  with  its  fascia. 

Relation. — Externally  with  the  panniculus  carnosus,  skin, 
triceps  extensor  brachii,  and  dorsal  trajoezius;  superiorly  with 
the  rhomboideus  brevis  and  dorsal  angle  of  the  scapula ;  inter- 
nally with  the  ribs,  serratus  magnus,  superficialis  costarum,  and 
gluteus  maximus. 

Action. — To  elevate  the  humerus,  and  thus  flex  the  shoulder- 
joint;  it  is  likewise  an  expiratory  muscle,  when  the  limb  is 
fixed. 


192  MYOLOGY 

SERRATtJS  MAGNUS. 

{Costo-suhacapularis. ) 

(PL.  III.  10.  15.) 

Situated  between  the  shoulder  and  chest,  and  on  the  side  of 
the  neck,  this  is  a  large  fan-shaped  muscle ;  it  may  be  divided 
into  a  cervical  and  a  costal  portion,  and  consists  of  several  bundles 
with  many  tendinous  intersections,  converging  upwards  to  the 
common  point  of  insertion. 

Origin. — Anteriorly,  from  the  transverse  processes  of  the  five 
posterior  cervical  vertebrae  ;  postero-inferiorly,  from  the  external 
surfaces  of  the  eight  true  ribs,  from  about  their  middles  to  their 
cartilages. 

Insertion. — Superiorly  to  the  venter  surface  of  the  scapula, 
between  the  origin  of  the  subscapularis  and  the  insertion  of  the 
rhomboidei. 

Relation. — Anteriorly  with  the  splenius ;  superiorly  with  the 
rhomboidei ;  supero-posteriorly  with  the  longissimus  dorsi ;  poste- 
riorly with  the  great  oblique  muscle  of  the  abdomen,  with  which 
it  interdigitates  ;  inferiorly  with  the  pectorals  ;  internally  with  the 
ribs,  longissimus  dorsi,  splenius,  cervical  vertebrae,  and  intercostals ; 
externally  with  the  subscapular  and  triceps  extensor  muscles. 

Action. — It  depresses  the  scapula  ;  when  the  limbs  are  fixed,  it 
elevates  the  neck,  and  is  also  a  subservient  muscle  of  inspiration ; 
but  it  chiefly  serves  with  its  fellow  as  a  muscular  sling,  in  which 
the  body  is  suspended  between  the  anterior  limbs. 

SUPERFICIALIS  COSTARUM. 

{Dorso-costalis.) 

(Pl.  II.  49.) 

Placed  on  the  supero-lateral  part  of  the  back,  this  muscle  is 
broad,  thin,  and  digitated,  and  consists  of  an  anterior  and  a 
posterior  portion. 

Origin. — Ajiteriorly,  from  the  supraspinous  ligament,  and  dorsal 
spines  from  the  second  to  the  thirteenth  inclusive;  posteriorly  from 
the  spines  of  the  last  eight  dorsal  and  anterior  lumbar  vertebrae. 

Insertion. — The  anterior  part  to  the  nine  ribs  behind  the 
fourth,  just  below  their  angles,  and  to  their  anterior  borders  ; 
the  posterior  part  to  the  posterior  borders  of  the  last  nine  ribs. 


EXPLANATION  OF  PLATE  IIL 

Muscles  of  the  Horse. 

Deep  Layer. 


1,  Temporalis. 

22.  Humeralis  obliquus. 

1 .  Stylo-maxillaris, 

22'.  Caput  parvum  (of  triceps  extensor 

2.  Rectus  capitis  anticus  major. 

brachii). 

3.  Stemo-thyro-liyoideiis. 

23.  Extensor  sufFraginis. 

4.  Sterno-maxillaris. 

24.Extensormetacarpimagnusdivided. 

5.  The  Trachea. 

25.  Extensor  metacarpi  obliquus 

6.  Scalenus. 

25'.  Its  tendon. 

7.  Spfenius. 

26,  28.  Flexor  pedis  perforaus  and  per* 

8.  Funicular   part   of    ligamentum 

foratus. 

nuchas. 

29.  Obliquus  abdominis  internus. 

9.  Rhomboideus  longus. 

30.  Gluteus  maximus.. 

10.  Cervical-) 

serratus  maguus. 
15.  Costal     / 

31.  Erector  coccygi.s. 

32.  Curvator  coccygis. 

11.  Cartilage  of  prolongation. 

33.  Depressor  coccygis. 

12.  Rhomboideus  brevis. 

34.  Rectus  femoris. 

13.  Transversalis  costarum. 

35.  Vastus  externus. 

14.  Longissimus  dorsi. 

36.  Part  covered  by  triceps  abductor. 

15.  Serratus  Magnus. 

37.  Biceps  rotator  tibialis. 

16.  External  intercostals. 

38.  Gastrocnemius  externus. 

17.  Internal  intercostals. 

39.  Plantaris. 

18.  Rectus  abdominis. 

40.  Flexor  pedis  perforans. 

19  19.  Pectoralis  magnus. 

41.  Peroneus. 

20.  Postea-spinatus  minor. 

42.  Flexor  metatarsi. 

21.  Flexor  brachii. 

43.  Extensor  pedis  (cut  across). 

COSTAL   REGION.  19? 

Relation. — Internally  with  the  ribs,  transversalis  costarum, 
and  longissimus  dorsi ;  externally  with  the  rhomboideus,  serratus 
magnus,  and  latissimus  dorsL 

Action. — Respiratory;  the  anterior  portion  drawing  the  ribs 
outwards  and  forwards,  acts  as  an  inspiratory,  the  posterior,  by 
drawing  them  backwards  and  upwards,  as  an  expiratory  muscle. 


TRANSVERSALIS  COSTARUM. 

(  Trachelo-costalis. ) 

(Pl.  IIL  13.) 

Situated  on  the  supero-lateral  part  of  the  thorax,  it  is  long, 
thin,  and  semipenniform,  the  fibres  passing  downwards,  outwards, 
and  forwards,  its  numerous  muscular  bundles  each  terminating 
in  a  flat  tendon. 

Origin. — From  the  transverse  processes  of  the  first  lumbar 
vertebrae,  and  the  ribs  near  their  tubercles. 

Insertion. — To  the  external  surface  of  all  the  ribs,  a  tendon 
to  each,  and  one  to  the  last  cervical  vetebra. 

Relation. — Externally  with  the  preceding  muscle ;  internally 
with  the  ribs;  superiorly  with  the  longissimus  dorsi. 

Action. — It  compresses  the  ribs,  assisting  in  expiration. 


LEVATORES  COSTARUM. 
(Transverso-costalis.) 

Situated  deeply  on  the  back,  these  muscles  are  small,  flat,  and 
triangular,  extending  obliquely  downwards  and  backwards.  They 
are  fleshy  and  tendinous. 

Origin. — Superiorly,  from  the  transverse  processes  of  the 
dorsal  vertebrae,  just  above  the  tubercles  of  the  ribs. 

Insertion. — Inferiorly  to  the  external  faces  of  the  ribs,  just 
above  their  angles. 

Relation. — Externally  with  the  longissimus  dorsi  ;  internally 
with  the  external  intercostals,  with  which  posteriorly  they  are 
much  blended. 

Action. — To  raise  and  draw  the  ribs  forwards,  thus  acting  as 
inspiratory  muscles. 

o 


194 


INTERCOSTALES. 

{Externi  and  Interni). 

(PL.  III.  16. 17). 

These  fill  up  the  spaces  between  the  ribs,  are  external  and 
internal,  and  usually  seventeen  in  number,  consisting  of  flat 
bands,  included  in,  and  intersected  by,  many  broad  aponeurotic 
slips.  The  external  ones  are  thickest  above,  the  internal  below, 
the  former  terminating  at  the  costal  cartilages,  between  which 
the  latter  extend. 

Origin. — From  the  posterior  border  of  each  rib. 

Insertion. — The  anterior  border  of  each  succeeding  rib,  the 
'fibres  of  the  external  ones  extending  downwards  and  backwards, 
those  of  the  internal  ones  downwards  and  forwards.  The  external 
terminate  at  the  costal  cartilages,  while  the  internal  do  not 
extend  above  the  angles. 

Relation — Externally  with  the  serratus  magnus,  superiicialis 
and  transversalis  costaruni,  and  latissimus  dorsi ;  internally  with 
the  pleura. 

Action. — They  are  inspiratory  muscles,  drawing  the  ribs  for- 
ward, the  first  rib  being  rendered  a  fixed  point  by  the  contraction 
of  the  scalenus.      They  thus  aid  the  diaphragm  in  its  action. 

Pectoral  Region. 
In  this  region  we  describe  two  groups  of  muscles,  the  'pectoral 
and  the  sternal,  the  latter  being  deep-seated. 

Pectoral  Group. 
This  group  consists  of  four  pairs  of  musclep.  which  are  largely 
developed  in  the  horse,  and  all  of  which  arise  from  the  external 
surface  of  the  sternum  and  its  appendages,  and  become  attached 
to  the  pectoral  limb,  upon  which  they,  as  a  group,  assist  in  sus- 
pending the  body,  also  in  moving  the  limb,  and  in  respiration. 
They  are  differently  described  by  different  authorities  ;  Percival 
and  Leyh  describe  three  pairs,  Chauveau  two,  but  as  the  latter 
divides  each  of  them  into  two  parts,  his  consideration  ultimately 
agrees  with  the  one  adopted  here.  We  describe  four  pairs  of 
pectoral  muscles  : — 

Pectoralis  transversus.       I       Pectoralis  anticup. 

Pectoralis  magnus.  |       Pectoralis  parvus. 


PECTORAL  GROUP. 


195 


PECTORALIS  TRANSVERSUS. 

(Sterno-aponeuroticus. ) 

(Fig.  75.  d.) 

Situated  on  the  latero-inferior  part  of  the  thorax,  this  muscle 
is  quadrilateral,  the  fibres  extending  outwards  and-  downwards. 


Fto.  75. 

Peetoral  muscles,  and  inferior  deep  muscles  of  the  neck,    a,  Longus  colli ;   h,  Rectus  capitis 

lateralis  ;   c,  Rectus  capitis  anticus  minor  ;  d,  Pectoralis  transversus  ;  e,  Pectoralis  antijcns  ;  //, 

Pectoralis  magnus ;  g,  Pectoralis  parTus.    On  the  left  side  the  pectoralis  transversus  and  anticus 

have  been  removed. 

Near  its  origin  it  is  fleshy,  mixed  with  tendon,  but.  afterwards 
becomes  aponeurotic. 

Origin. — By  fleshy  fibres  usually  from  the  first  four  bones  of 
the  sternum,  meeting  its  fellow  at  a  white  central  line. 

Insertion. — To  the  olecranon,  by  fascia  covering  the  inner  side 
of  the  arm,  and  to  the  anterior  part  of  the  humerus. 

Relation. — Externally  with  the  skin ;  anteriorly  with  •  the 
pectoralis  anticus ;   superiorly  with  the  pectoralis  magnus. 

Action. — To  adduct  the  arm,  and  especially  to  tense  the 
"brachial  fascia. 


196  MYOLOGY. 

PECTORALIS    MAGNUS. 

(Sterno-trochineus. ) 

(Pl.  III.  19,  19.    Fig.  75.//.) 

This  muscle  is  situated  on  the  infero-lateral  part  of  the  thorax, 
and  is  large,  irregularly  four-sided,  flat,  and  thick,  the  fibres 
extending  forwards  and  outwards.  Slightly  aponeurotic  ante- 
riorly, elsewhere  it  is  fleshy. 

Origin. — From  the  inferior  border  of  the  last  three  or  four 
bones  of  the  sternum,  the  ensiform  cartilage,  and  its  fellow  of  the 
opposite  side ;  externally  from  the  cartilages  of  the  false  ribs, 
fascia  of  the  external  oblique  muscle  of  the  abdomen,  and  the 
abdominal  tunic. 

Insertion. — To  the  fascia  on  the  inside  of  the  arm,  and  to  the 
inner  trochanter  of  the  humerus,  under  the  tendon  of  the  coraco- 
humeralis,  and  by  fascia  over  the  bicipital  groove,  to  the  external 
trochanter. 

Relations. — Externally  with  the  panniculus,  skin,  and  pectoralis 
transversus ;  internally  with  the  fascia  of  the  external  oblique, 
and  the  ribs  ;  anteriorly  with  the  pectoralis  parvus. 

Action. — To  draw  the  shoulder  back  and  adduct  the  arm  ;  in 
difficult  respiration  it  acts  as  an  inspiratory  muscle. 

PECTORALIS   ANTICUS. 

{Sterno-humeraiis. ) 

(Fig.  75.  e.) 

Situated  on  the  anterior  part  of  the  breast,  it  forms  the  fleshy 
prominence  seen  in  front.  Short,  thick,  and  fusiform,  its  fibres 
extend  outwards  ;  it  is  tendinous  at  its  attachments,  with  a  fleshy 
belly. 

Origin. — From  the  cariniform  cartilage  and  first  bone  of  the 
€tenium.  It  is  directed  somewhat  backwards,  outwards,  and 
■downwards. 

Insertion. — To  a  ridge  on  the  anterior  part  of  the  shaft  of  the 
humerus  by  fleshy  fibres,  and  an  aponeurotic  tendon  common  also 
to  the  levator  humeri,  and  pectoralis  transversus. 

Relations. — Externally  with  the  skin  ;  anteriorly  with  the 
levator  humeri  and  panniculus ;  posteriorly  with  the  pectoralis 
magnus  and  transversus ;  internally  with  the  parvus. 

Action. — Its  chief  action  is  to  adduct  the  arm. 


STERNAL   GROUP,  197 


PECTORALIS   PARVUS. 


(jSterno-prescapularis. ) 
(Fig.  75.  g.) 

In  front  of  the  magnus,  on  the  antero-iuferior  part  of  the 
Ihorax,  elongated  and  prismatic  in  form,  its  fibres  extend  out- 
wards, forwards,  and  upwards  ;  it  is  tendinous  at  its  origin,  fleshy 
elsewhere. 

Origin. — From  the  three  or  four  anterior  sternal  segments, 
cartilages,  ribs,  and  carinifori^  cartilage. 

Insertion. — To  the  fascia  in  front  of  the  shoulder-joint,  and 
the  anterior  costa  of  the  scapula,  nearly  as  high  up  as  the  origin 
of  the  antea-spinatus. 

Relation. — Externally  with  the  magnus  and  transversus ; 
inferiorly  with  the  transversus  and  anticus ;  internally  with  the 
first  costal  cartilages,  intercostales,  and  transversalis  costarum  ; 
anteriorly  with  the  levator  humeri. 

Action. — To  draw  the  shoulder-joint  backwards  and  down- 
wards, assist  the  magnus,  and  tense  the  scapular  fascia. 

Sternal  Group. 
The  muscles  of  this  unimportant  group  are  two  in  number — 

Lateralis  stern  i. 
Triangularis  sterni. 

LATERALIS    STERNL 
{Costo-sternalis. ) 

Placed  along  the  inferior  border  of  the  serratus  magnus,  its 
^fibres  extend  downwards  and  backwards.  It  is  flat,  thin,  and 
aponeurotic  at  its  extremities. 

Origin. — From  the  outer  surface  of  the  first  rib,  passing  over 
the  next  two  or  three  ribs,  and  becoming  attached  to  the  ster- 
num at  about  the  fourth  segment. 

Relation. — Externally  with  the  pectorals ;  superiorly  with  the 
serratus  magnus ;  posteriorly  with  the  rectus  abdominis ;  inter- 
nally with  the  ribs  and  intercostals. 

Action. — An  auxiliary  muscle  of  expiration. 


198  MYOLOGY. 

TRIANGULARIS  STERNI. 

{Sterno-costalis.) 

Situated  in  the  thorax  and  upon  the  steraum,  it  is  triangular^ 
tendinous,  and  dentated  on  its  outer  border. 

Origin. — From  the  superior  sternal  ligament  and  segments. 

Insertion. — To  the  cartilages,  and  inner  surfaces  of  the  distal 
ends  of  the  true  ribs,  e.Kcepting  the  first. 

Action. — To  assist  in  expiration. 

DORSO-LUMBAR    REGION. 

The  muscles  of  this  region,  a  smgle  group,  are  closely  related 
with  the  superior  aspect  of  the  vertebral  column,  and  we  describe 
them  as  consisting  of  four — 

Longissimus  dorsi.  I     Semispinalis  dorsi  et  lumborum. 

Spinalis  dorsi.  |     Intertransversales  lumborum. 

LONGISSIMUS  DORSI. 

(Ilio-spinalis.) 

(Pl.  in.  14.) 

Situated  on  the  superior  part  of  the  back  and  loins,  this,  the 
longest  and  most  powerful  muscle  in  the  body,  occupies  the  space 
between  the  costal  angles  and  the  dorso-lumbar  spines ;  broad 
and  fleshy  at  its  origin  in  the  loins,  it  becomes  deeper  and 
narrower  as  it  proceeds  forwards.  Towards  the  withers  it  diverges, 
presenting  three  distinct  portions,  two  of  which  proceed  in  an 
oblique  direction  to  the  neck,  and  terminate  by  several  tendons 
(the  deeper  portion  is  described  as  the  spinalis  dorsi) ;  the  third 
portion  is  adherent  to  the  sides  of  the  anterior  dorsal  spines.  The 
belly  of  this  muscle  is  intersected  by  several  tendons,  and  is  invested 
posteriorly  by  a  very  strong,  tendinous  aponeurosis. 

Attachments. — The  crest,  inner  surface,  and  supero-anterior 
spine  of  the  ilium ;  the  spinous  and  transverse  processes  of  the 
first  two  bones  of  the  sacrum ;  the  spinous,  transverse,  and 
oblique  processes  of  all  the  lumbar  vertebrae  ;  the  spinous  and 
transverse  processes  of  all  the  dorsal  vertebrse;  the  external 
surface  of  the  last  fifteen  or  sixteen  ribs  just  above  the  trans- 
versalis  costarum,  and  the  spinous  and  transverse  processes  of 
the  last  three  or  four  cervical  vertebrse. 


DOESO-LUMBAR    REGIOM.  199 

Relation. — Externally  with  the  superficialis  cdstarum,  and 
gluteus  maximus  which  overlaps  it  in  the  lumbar  region;  in- 
feriorly  with  the  transversalis  costarum ;  internally  with  the  ribs, 
vertebrae,  and  semispinalis  dorsi  et  lumborum ;  anteriorly  with 
the  spinalis  dorsi. 

Action. — It  is  brought  powerfully  into  play  in  kicking  and 
rearing,  by  elevating  the  fore  or  hind  quarters,  according  to 
whether  the  fore  or  hind  limbs  are  fixed.  Acting  singly,  the 
result  is  lateral  flexion  of  the  back  and  loins.  It  may  assist  also 
in  expiration. 

SPINALIS  DORSI.'"* 

Situated  deeply  on  the  withers,  it  is  pyramidal  in  form, 
aponeurotic  at  its  origin,  with  a  fleshy  belly ;  it  is  with  difficulty 
separated  from  the  longissimus  dorsi. 

Origin. — By  aponeurosis  from  the  supraspinous  ligament,  as 
far  back  as  the  twelfth,  and  from  the  posterior  borders  of  the 
spinous  processes  of  the  six  anterior  dorsal  vertebrae. 

Insertion. — To  the  superior  spinous  processes  of  the  last  three 
or  four  cervical  vertebrae. 

Relation. — Externally  with  the  trapezius  and  rhomboideus 
brevis ;  anteriorly  with  the  complexus  major  and  splenius ;  infe- 
riorly  with  the  longissimus  dorsi ;  internally  with  its  fellow,  the 
ligamentum  nuchas,  the  anterior  dorsal  vertebrae,  and  semispinalis 
dorsi. 

Action. — To  assist  in  elevating  the  neck. 


SEMISPINALIS   DOESI   ET   LUMBORUM. 
{Spinalis  Transversus.) 

In  contact  with  the  dorsal  and  lumbar  spines,  this  muscle  con- 
sists of  a  number  of  fasciculi,  whose  fibres  are  directed  upwards 
and  forwards. 

Origin. — From  the  sacrum,  the  oblique  processes  of  all  the 
lumbar,  and  transverse  processes  of  all  the  dorsal  vertebrae. 

Insertion. — The  spinous  processes  of  the  vertebrae,  the 
fasciculi  each  passing  over  two  or  three  spines  before  being 
inserted;  it  becomes  continuous  with  the  spinalis  colli  at  the 
seventh  cervical. 

*  [Tliis  muscle  may  be  regarded  as  part  of  tlie  longissimus  dorsL— Ed.] 


200  MYOLOGY. 

Relation. — Externally  with  the  longissimus  dorsi ;  internally 
with  the  vertebrae. 

Action. — To  assist  in  extending  the  spine. 

INTERTRANSVERSALES   LUMBORUM. 

These  are  small  muscular  slips,  invested  by  strong  tendinous 
fasciae,  running  from  the  transverse  process  of  one  lumbar  vertebra 
to  the  one  adjacent. 

Relation. — "With  the  longissimus  dorsi  and  intertransverse 
ligaments. 

Action. — To  assist  in  flexing  the  spine  laterally,  by  bringing 
these  processes  nearer  to  each  other. 

Abdominal  Region. 

The  infero-lateral  walls  of  the  abdomen  are  formed  by  a  large 
musculo-aponeurotic  envelope,  consisting  of  four  pairs  of  muscles, 
covered  externally  by  the  abdominal  tunic,  the  muscles  on  the 
right  being  separated  from  those  on  the  left  by  the  linea  alba,  a 
white  fibrous  cord  extending  from  the  sternum  to  the  pubis.  These 
muscles,  the  rectus  excepted,  consist  each  of  a  fleshy  and  an 
aponeurotic  portion,  and  the  general  line  of  demarcation  between 
the  aponeurotic  and  the  fleshy  region  is  known  as  the  linea 
semilvmaris.     We  have  to  describe  the  following  structures  : — 

Tunica  abdominalis. 

Linea  alba. 

Muscles. 
Obliquus  abdominis  externus.        I      Rectus  abdominis, 
Obliquus  abdominis  internus,        |      Transversalis  abdominis. 

TUNICA   ABDOMINALIS. 

(Tunica  Elasiica). 

The  abdominal  tunic  is  an  immense  expansion,  composed  of 
yellow  elastic  tissue,  which  covers  the  external  oblique  muscles. 
It  is  thickest  at  the  pubis,  and  on  each  side  of  the  linea  alba, 
thinning  as  it  approaches  the  sternum,  and  disappearing  at  the 
posterior  attachment  of  the  pectoralis  magnus  muscle.  It  blends 
with  the  external  oblique,  anteriorly  reaching  the  digitations  of 


ABDOMINAL   REGION.  201 

the  serratus  magnus ;  posteriorly  it  furnishes  a  few  fibres,  which, 
detached  from  the  surface  of  the  common  abdominal  tendon 
(prepubian),  pass  between  tne  thighs,  and  become  lost  in  the 
muscles  of  that  region. 

Relation. — Externally  by  cellular  tissue  to  the  panuiculus  and 
skin.  It  is  continuous  with  the  suspensory  ligament  of  the  sheath 
and  dartos  in  the  male,  and  the  elastic  envelope  of  the  mamma 
in  the  female,  in  whom  it  is  always  thickest. 

Use. — To  afford  a  mechanical  support  to  the  abdominal 
viscera,  and  conserve  muscular  action  by  substituting  elasticity 
for  it.  On  the  application  of  distensile  force  it  yields  con- 
siderably. 

LINEA   ALBA. 

The  linea  alba  is  a  white  fibrous  cord  situated  between  the 
inner  borders  of  the  two  recti-abdominales,  to  which  it  gives 
attachment,  as  to  the  other  abdominal  muscles.  Anteriorly  it  is 
attached  to  the  inferior  surface  of  the  xiphoid  cartilage,  and 
posteriorly  it  becomes  cenfounded  with  a  large  tendon,  common 
to  the  abdominal  muscles,  the  prepubian  tendon,  which  is 
-attached  to  the  anterior  border  of  the  pubis,  and  assists  in 
the  formation  of  the  internal  commissure  of  the  inguinal  canals. 
Between  its  posterior  and  middle  third  the  linea  alba  is  enlarged, 
and  forms  a  lozenge-shaped  space,  in  the  centre  of  which  is  the 
remnant  of  the  umbilicus.  The  fact  of  this  structure  joining  the 
sternum  to  the  pubic  symphysis,  together  with  certain  co-related 
features,  has  induced  anatomists  to  regard  the  linea  alba  as 
representing  a  rudimentary  abdominal  sternum. 


OBLIQUUS  ABDOMINIS  EXTERNUS. 
(Costo-abdominalis. ) 
(PL.  XL  74.) 
The  largest  and  most  external  muscle  of  the  group,  situated  on 
the  infero-lateral  aspect  of  the  abdomen,  and  consisting  of  a  fleshy 
and   an  aponeurotic  portion.      It  is  quadrilateral,  its  fibres  run- 
ning downwards  and  backwards.     Its  aponeurosis  commences  at 
a  line  called  the  linea  semilunaris,  and  is  continued  to  the  linea 
alba,  where  it  bends  with  that  of  the  internal  oblique. 

Attachments. — By  fleshy  fibres,  anteriorly  to  the  outer  surface 
of  the  last  thirteen  or  fourteen  ribs,  just  below  their  middle  ;  the 


202  MYOLOGY. 

four  anterior  digitations  are  received  between  the  corresponding 
ones  of  the  serratus  maguus  ;  to  the  fascia  of  the  latissimus  dorsi^ 
and  superiorly  to  the  lumbar  fascia  :  to  the  anterior  iliac  spine 
and  crest ;  to  the  pubis  and  prepubian  tendon,  and  inferiorly  to 
the  linea  alba  throughout  its  whole  extent. 

Relation. — Externally  with  the  abdominal  tunic ;  antero- 
externally  with  the  pectoralis  magnus ;  internally  with  the  ribs, 
cartilages,  and  intercostals,  the  internal  oblique  and  the  rectus ; 
anteriorly  with  the  serratus  magnus. 

Action. — To  support  and  compress  the  abdominal  viscera,  and 
assist  in  defecation,  urination,  and  parturition.  It  is  also  a 
flexor  of  the  vertebral  column,  and  a  muscle  of  expiration. 


APONEUROSIS  OF  THE  OBLIQUUS  EXTERNUS. 

The  distribution  of  this  aponeurosis  being  very  singular  and 
important,  it  merits  separate  consideration.  It  stretches  from 
the  anterior  spine  of  the  ilium  to  the  pubis,  answers  to  the 
fold  of  the  groin,  and  marks  the  division  between  the  trunk 
and  hind  extremity.  Posteriorly  it  splits  into  two  layers  ;  one 
descends  internally  over  the  thigh,  forming  the  crural  aponeurosis; 
the  other  is  reflected  upward,  and  enters  the  abdomina^  cavity, 
this  fold  receiving  the  name  of  the  crural  arch  or  Pouparfs 
ligament.  JSTear  the  prepubian  tendon,  and  immediately  in 
front  of  its  division,  the  aponeurosis  is  pierced  by  a  large  oval 
aperture,  the  external  abdomival  ring,  which  is  the  external 
opening  of  the  inguinal  canal. 

Crural  Aponeurosis. 

This  descends  over  the  fold  of  the  groin  to  the  patella,  and 
internal  surface  of  the  thigh,  blending  outwardly  with  the  fascia 
lata,  and  internally  becoming  less  dense  in  structure :  it  covers 
the  sartorius.  part  of  the  gracilis,  vastus  internus,  and  the  crural 
vessels  as  they  leave  the  abdomen. 

Poupart's  Ligament 

The  Crural  Arch  or  Pouparfs  Ligament  is  a  ribbon-shaped 
reflected  portion  of  the  aponeurosis  of  the  external  oblique,  and  is 
attached  by  its  extremities  to  the  anterior  spine  of  the  ilium,  and 
anterior  border  of  the  pubis.     Anteriorly  it  forms  the  posterior 


ABDOMINAL    REGION.  203 

pillar  of  the  inguinal  canal,  and  externally  gives  attachment  to 
the  posterior  fibres  of  the  internal  oblique.  Posteriorly  it  contacts 
the  sartorius  and  pectineus  muscles,  and  the  crural  vessels, 
embracing  those  parts  in  a  sort  of  arch,  hence  its  name.  Its 
superior  border  at  its  external  half  is  attached  to  the  lumbo-iliac 
aponeurosis ;  while  its  middle  is  confounded  with  the  external 
surface  of  the  sartorius  and  iliacus.  Inside  the  attachments 
of  the  pectineus  and  psoas  parvus,  it  forms,  with  the  anterior 
border  of  the  pubis,  the  iliacus  and  sartorius,  a  triangular  open- 
ing called  the  crural  ring,  through  which  the  crural  vessels  pass 
out  of  the  abdomen.  The  inferior  border  is  continuous  with  the 
femoral  and  great  oblique  aponeuroses. 

Inguinal  Canal. 

The  Inguinal  Canal  is  infundibuliform  and  compressed 
laterally ;  through  it  pass  the  spermatic  cord  and  external 
pudic  artery  of  the  male,  and  mammary  vessels  of  the  female. 
It  is  situated  obliquely  between  the  crural  arch,  which  is 
its  posterior,  and  the  internal  oblique  muscle,  which  forms 
its  anterior  wall.  The  external  orifice  is  called  the  external 
abdominal  ring,  and  is  larger  than  the  internal,  being  oval  in 
fornv  and  directed  backwards  and  inwards.  It  presents 
two  pillars  and  two  extremities  or  commissures.  The  pillars, 
anterior  and  posterior,  are  merely  the  edges  or  lips  of  the 
aperture,  and  are  formed  by  the  arciform  fibres  of  the 
aponeurosis  of  the  external  oblique  muscle,  the  posterior  one 
being  assisted  by  Poupart's  ligament.  The  commissures,  external 
and  internal,  are  formed  by  the  union  of  the  pillars,  the  latter 
being  limited  by  the  prepubian  tendon.  The  peritoneal  or 
internal  abdominal  ring,  the  internal  orifice  of  the  canal,  is 
situated  in  front  of  the  crural  ring.  It  is  a  mere  dilatable  cleft 
between  the  crural  arch  and  the  internal  oblique,  and  but 
indifferently  marked  at  its  extremities. 

OBLIQUUS   ABDOMINIS   INTERNUS. 

(Ilio-abdominalis. ) 

(PL.  III.  29.) 

Situated  under  the  externus,  on  the  postero-lateral  and  inferior 

aspects  of  the  abdomen,  its  fibres  expanding  downvrards,  it  is, 

like  the  externus,  fleshy  and  aponeurotic ;  the  fleshy  portion  is 


204  MYOLOGr. 

thick,  and  occupies  the  flank  ;  the  aponeurosis  commences  at  the 
linea  semilunaris,  its  fibres  bknding  with  those  .of  the  external 
oblique. 

Attachments. — Supero-posteriorly,  to  the  anterior  spine  of  the 
ilium,  whence  its  fleshy  fibres  radiate  ;  a  portion  is  attaqjied  to 
the  transverse  processes  of  two  or  three  of  the  first  lumbar 
vertebrae,  and  passes  to  the  posterior  border  of  the  last  rib  (this 
portion  is  described  by  the  German  anatomists  as  a  retractor 
costce)  ;  and  to  the  fascia  of  the  latissimus  dorsi ;  to  the  cartil- 
ages of  the  false  ribs  ;  postero-inferiorly  to  the  symphysis  pubis, 
by  the  prepubian  tendon,  aiding  in  the  formation  of  the  internal 
abdominal  ring ;  inferiorly  to  the  linea  alba  throughout  its  whole 
extent. 

Relations. — Externally  with  the  external  oblique  ;  internally 
with  the  transversalis  and  rectus  abdominis. 

Action. — It  assists  the  externus  in  compressing  the  abdomen 
in  the  act  of  respiration,  and  in  flexing  the  spine.  It  also  draws 
the  last  rib  backwards. 

RECTUS    ABDOMINIS. 

(Steroio-pubialis. ) 

(Pl.  III.  18.) 

Situated  along  the  inferior  and  middle  part  of  the  abdomen,  it 
is  long,  flat,  polygastric,  and  broadest  in  the  middle.  Tendinous 
at  its  attachments,  its  belly  consists  of  numerous  flat  muscular 
fasciculi,  with  transverse  tendinous  intersections,  to  which  the 
aponeuroses  of  the  oblique  muscles  are  adherent  ;  these  intersec- 
tions are  called  the  linece  transversce  (inscriptiones  tendinece), 
and  may  be  regarded  as  the  abdominal  representatives  of  the  ribs. 
The  posterior  part  of  the  muscle  assists  in  the  formation  of  the 
internal  abdominal  ring. 

Attachments. — Anteriorly  to  the  inferior  surface  of  the  xiphoid 
cartilage  and  sternum  ;  to  the  cartilages  of  the  last  four  true  and 
first  two  false  ribs ;  posteriorly  to  the  crest  of  the  pubis,  through 
the  medium  of  the  prepubian  tendon,  which  is  directly  continuous 

with  it  ;  internally  to  the  linea  alba. 

Relations. — Inferiorly  with   the    aponeurosis    of  the   internal 

oblique  muscle  ;  anteriorly  with  the  pectoralis  magnus  ;  superiorly 

with  the  transversalis,  and  the  cartilages  of  nearly  all  the  ribs ; 

internally  with  its  fellow  at  the  linea  alba. 


SUBLIIMBAR    REGION.  205 

Action. — To  support  and  compress  the  abdominal  viscera  and 
assist  in  respiration.     It  is  the  chief  flexor  of  the  spinal  column. 

TRANSVERSALIS   ABDOMINIS. 
(Lumbo-abdominalis. ) 

Placed  on  the  infero-lateral  aspect  of  the  abdomen,  imme- 
diately outside  the  peritoneum,  this  muscle  is  broad,  flat,  and 
quadrilateral,  its  fibres  extending  downwards.  It  is  fleshy 
from  its  origin  to  the  linea  semilunaris,  where  it  becomes 
aponeurotic. 

Attachments. — To  the  transverse  processes  of  the  lumbar 
vertebrae,  and  the  inner  surface  of  the  cartilages  of  the  false  ribs, 
interdigitating  with  the  attachments  of  the  diaphragm,  and  by 
its  aponeurosis  to  the  xiphoid  cartilage  and  linea  alba,  becoming 
rudimentary  posteriorly. 

Relations. — Anteriorly  with  the  diaphragm ;  externally  with 
the  cartilages  of  the  false  ribs,  the  obliquus  internus  and  rectus  ; 
internally  with  a  thin  layer  of  fascia  (the  fascia  transversalis) 
which  connects  it  with  the  peritoneum. 

Action. — To  assist  the  oblique  muscles,  and  raise  the  viscera. 

SUBLUMBAR   REGION". 

The  muscles  of  this  region,  a  single  group,  connect  the  lumbar 
and  last  dorsal  vertebrae  with  the  pelvis  or  the  posterior  limb.  They 
are  covered  by  the  iliac  fascia,  and  this  by  the  peritoneum,  a 
serous  membrane  lining  the  abdominal  cavity.  In  this  group  we 
place  four  muscles  : — 

Psoas  magnus.  I  Iliacus. 

Psoas  parvus.  |  Quadratus  lumborum, 

PSOAS   MAGNUS. 

{Sublumbo-trochantineus.) 

(Fig.  76.  c.) 

Situated  below  the  transverse  processes  of  the  lumbar  vertebrae, 
it  is  elongated  and  fusiform,  flattened  anteriorly,  conical  posteriorly, 
its  ■  fibres  extending  downwards  and  backwards  ;  it  is  almost 
entirely  fleshy,  except  at  its  insertion. 

Origin. — From  the  inferior  surfaces  of  the  last  two  ribs,  the 


206  MYOLOGY. 

bodies  of  the  last  two  dorsal,  and  all  the  lumbar  vertebrae  except 
the  last,  and  to  the  lumbar  transverse  processes,  passing  between 
the  two  parts  of  the  iliacus. 

Insertion. — By  a  tendon,  common  to  it  and  the  iliacus,  to  the 
internal  trochanter  of  the  femur. 

Relation. — Posteriorly  with  the  iliacus  ;  internally  with  the 
psoas  parvus  and  the  bodies  of  the  vertebrae;  above  with  the 


Fia.  76. 
Muscles  of  the  sublumbar  and  internal  deep  femoral  regions— seen  from  below,    a,  a.  Quadratus 
lumborum ;  6,  Psoas  parvus  ;  c,  Psoas  magnus ;  d.  e,  Iliacus  ;  /,  Pectineus  ;  g,  Adductor  brevis  ; 
h,  Adductor  longus ;  i,  Adductor  magnus  ;  fc,  Vastus  internus :  I,  Kectus  femorls. 

quadratus  lumborum,  and  below  with  the  kidney  and  iliac  fascia, 
the  diaphragm,  and,  in  the  thoracic  cavity,  with  the  pleura. 

Action. — To  flex  and  rotate  the  thigh,  or,  the  latter  being 
fixed,  to  flex  the  loins ;  the  latter  action  tends  to  "  roach  "  the 
back,' 

PSOAS   PARVUS. 

{Suhlumho-puhialis. ) 

(Fig.  76.  6.) 

Situated  on  the  inner  side  of  the  psoas  magnus,  it  is  long,  thin, 

and  semipenniform,  the  fibres  extending  backwards  and  outwards. 


SUBLUMBAR    REGION.  207 

Tleshy  above,  it  has  posteriorly  a  strong  flat  tendon  passing  along 
the  lower  surface  to  its  insertion. 

Origin. — From  the  bodies  of  the  last  three  or  four  dorsal, 
and  all  the  lumbar  vertebras. 

Insertion. — To  the  ilio-pectineal  eminence  on  the  brim  of 
the  pubis,  midway  between  the  symphysis  and  the  acetabulum, 
and  to  the  iliac  fascia. 

Relation. — Inferiorly  with  the  diaphragm,  pleura,  posterior 
aorta  and  vena  cava  ;  externally  with  the  psoas  magnus. 

Action. — To  flex  the  pelvis  on  the  ppine,  when  the  loins  are 
fixed  ;  when  the  pelvis  is  fixed,  to  arch  the  back.  It  is  also  the 
tensor  of  the  iliac  fascia. 

ILIACUS. 

(Ilio-trochantineus.) 

(Fig.  76.  d,  e.) 

Situated  under  the  false  pelvis,  this  muscle  is  strong,  thick, 
-and  pyramidal,  the  base  being  forwards,  and  the  fibres  extending 
downwards,  backwards,  and  inwards.  The  belly  is  incompletely 
divided  by  a  fissure  into  two  unequal  portions,  the  external  being 
the  larger;  through  this  fissure  passes  the  tendon  of  the  psoas 
magnus,  which  its  own  tendon  joins. 

Origin. — From  the  ilio-pectineal  ridge,  nearly  all  the  venter 
surface  of  the  ilium,  and  the  inferior  sacro-iliac  ligament. 

Insertion. — To  the  internal  trochanter  of  the  femur,  along  with 
the  psoas  magnus. 

Relation. — Superiorly  with  the  ilium  ;  inferiorly  with  the  iliac 
fascia  and  sartorius  ;  externally  with  the  tensor  fasciae  latse  and 
rectus  femoris,  from  which  it  is  separated  by  a  layer  of  fat ; 
internally  with  the  crural  vessels.  It  passes  between  the  vastus 
internus  and  the  pectineus. 

Action. — To  flex  the  femur,  and  rotate  it  outwards. 

QUADRATUS   LUMBORUM. 

{Sacro-lumbalis. ) 

(Fig.  76.  a.) 

Placed  below  and  between  the  lumbar  transverse  processes,  this 
is  a  flat,  thin  muscle,  consisting  of  several  bundles,  with  strong 
tendinous  intersections.     The  principal  bundle  is  situated  exter- 


208  MYOLOGY. 

nally  and  longitudinally,  the  lesser  ones  diverging  from  it  inwards- 
and  forwards, 

Oingin. — The  chief  bundle  arises  from  the  inferior  sacro-iliac 
ligament  at  the  angle  of  the  sacrum,  passing  directly  forwards. 

Insertion. — To  the  posterior  border  of  the  last  rib,  becoming 
attached  in  its  course  to  the  free  extremities  of  the  transverse 
processes  of  the  lumbar  vertebrae.  The  other  bundles  leave  the 
internal  border  of  the  first,  and  are  attached  to  most  of  the  trans- 
verse processes  of  the  lumbar  vertebrae,  and  inner  surfaces  of  the 
last  two  or  three  ribs. 

Relation. — Superiorly  with  the  vertebrae,  and  intertransversales 
liimborum  ;  inferiorly  with  the  psoas  magnus. 

Action. — To  assist  in  lateral  flection  of  the  lumbar  vertebrae, 
and  to  draw  the  last  ribs  backwards. 


Diaphragmatic  Region. 

This  region  contains  only  one  muscle,  from  which  it  takes  it» 
name. 

DIAPHRAGM. 

(Diaphragma.) 

(Fig.  77.  A.) 

The  diaphragm,  or  midrif,  is  the  muscular  partition  whiob 
separates  the  thorax  from  the  abdomen  ;  it  slopes  obliquely  down- 
wards and  forwards,  and  is  in  form  elliptical,  or  somewhat  heart- 
shaped,  being  widest  superiorly.  The  thoracic  surface  is  convex 
and  covered  with  pleura,  the  abdominal  concave  and  covered  with 
peritoneum.  It  is  divided  into  a  body  or  septum,  and  two  crura 
or  appendices ;  the  body,  or  greater  muscle,  is  made  up  of  a  fleshy 
periphery  and  tendinous  phrenic  centre  (Speculuvo  Helmontii). 

Attachments. — The  fleshy  portion  is  attached  to  the  inner 
surface  of  the  distal  ends  of  the  last  twelve  ribs,  or  to  their 
cartilages,  and  to  the  superior  surface  of  the  ensiform  cartilage, 
the  fibres  converging  towards  the  tendinous  centre.  The  crura  ot 
pillars,  two  in  number,  lie  below  the  vertebrae  in  the  sublumbar 
region.  The  right  is  the  longer  and  larger,  and  arises  from  tho 
inferior  surface  of  the  bodies  of  all  the  lumbar  vertebrre  but  the 
last,  by  strong  tendinous  fibres  which  blend  with  the  inferior 
common  ligament.  The  left  differs  from  the  right  in  arising 
from  only  one  or  two  anterior  lumbar  vertebrae.      The  crura  pass 


DIAPHRAGMATIC    REGION.  209^ 

down  the  central  line  of  the  tendinous  portion,  and  gradually 
blend  with  its  fibres.  Near  the  centre-  of  the  diaphragm,  and  a 
little  to  the  right,  is  a  large  opening,  the  foramen  dextrum^ 
through  which  passes  the  posterior  vena  cava.  Between  the 
pillars  superiorly  is  a  second  opening,  the  hiatus  aorticus,  through 
which  pass  the  posterior  aorta,  vena  azygos,  and  thoracic  duct. 
Below  this,  the  right  crus  forms  towards  the  left  a  third  opening, 
the  foramen  sinistrum,  for  the  passage  of  the  oesophagus  and 
pneumogastric  nerves,  accompanied  by  the  pleural  artery.     There 


Fig.  77. 

The  diaphragm,  and  superficial  muscles  of  the  internal  femoral  region— viewed  from  belowr 
A,  The  diaphragm  ;  a  a,  The  tendinous  centre  ;  a'  a'.  The  fleshy  periphery;  a"  a"i  The  crura; 
a'",  The  hiatus  aorticus ;  a"".  The  foramen  sinistrum  ;  a""'.  The  foramen  dextrum  ;  &,  The  sar- 
torias  ;  c,  The  gracilis. 

are  thus  three  openings — the  hiatus  aorticus  above,  the  foramen 
sinistrum  in  the  middle,  and  the  foramen  dextrum  below. 
Certain  of  the  sublumbar  muscles  originate  partly  in  the  thorax, 
and  the  diaphragm  forms  arches  which  allow  their  passage,  and 
that  of  the  sjonpathetic  and  splanchnic  nerves ;  these  arches  are 
bouiided  by  ligaments,  the  ligamenta  arcuata ;  outside  the  arches, 
the  diaphragm  is  attached  to  the  last  rib  by  a  broad  fold  ot 
elastic  tissue. 

Relation. — Anteriorly  with  the  pleura,  which  covers  Doth  it 

p 


210  MYOLOGY. 

and  the  lungs ;  posteriorly,  covered  by  peritoneum,  it  contacts  the 
liver,  stomach,  spleen,  and  the  large  colon. 

Action. — Essentially  a  muscle  of  inspiration.  When  it  eon- 
tracts  it  becomes  flattened,  forces  the  abdominal  viscera  back- 
wards, and  so  enlarges  the  thoracic  cavity.  This  action  is 
antagonistic  to  one  of  the  actions  of  the  abdominal  muscles.  It 
also  assists  in  the  expulsive  efforts  of  defecation  and  parturition. 

Coccygeal  Kegion. 

The  muscles  of  this  region,  that  of  the  tail,  are  enclosed  in 
strong  fascia,  which  may  be  said  to  be  continuous  with  the 
approximate  pelvic  ligaments.  We  find  one  group  containing 
four  muscles  : — 

Erector  coccygis.  I  Curvator  coccygis. 

Depressor  coccygis.  I  Compressor  coccygis. 

ERECTOR   COCCYGIS. 

{Sacro-coccygeus  Superior.) 

(Pl.  IIL31.) 

Situated  on  the  supero-lateral  part  of  the  tail,  it  consists  of 
bundles  of  fibres,  intersected  by  tendons,  which  gradually  diminish 
in  size  from  before  backwards,  each  terminating  in  a  short  tendon. 

Origin. — The  tuberous  summits  and  lateral  aspect  of  the 
posterior  sacral  spines,  and  superior  surface  of  the  coccyx. 

Insertion. — To  the  coccygeal  bones. 

Relation. — Internally  with  its  fellow,  and  the  coccygeal  verte- 
bra ;  externally  with  the  skin  and  fascia. 

Action. — When  acting  together  to  elevate  the  tail;  singly,  to 
draw  it  upwards  and  outwards. 

DEPRESSOR   COCCYGIS. 

(Sacro-coccygeus  Inferior.) 

(Pl.  in.  33.) 

Situated  on  the  infero-lateral  aspect  of  the  tail,  and  similar  to 
the  erector,  but  thicker. 

Origin. — Within  the  pelvis,  from  the  inferior  surface  of  the 
sacrum,  the  inner  surface  of  the  sacro-sciatic  ligament,  and  the 
-coccygeal  vertebrae. 


MUSCLES    OF    THE    LIMBS.  211 

Insertion. — By  tendons  to  the  inferior  surface  of  all  the 
coccygeal  vertebrae  successively. 

Relation. — Superiorly  with  the  sacrum,  coccyx,  and  curvator ; 
ioferiorly  with  the  rectum  ;  externally  with  the  curvator  and 
sacro-sciatic  ligament ;  internally  with  its  fellow. 

Action. — To  bend  the  tail  downwards ;  singly,  to  draw  it 
downwards  and  to  one  side. 


CURVATOR   COCCYGIS. 

{Sacro-coccygeus  Lateralis.) 

(PL.  IIL  32.) 

Situated  on  the  side  of  the  tail,  and  similar  in  structure  to  the 
preceding,  it  is  merely  a  continuation  of  the  semispinalis  lumborum. 

Oricfin. — From  the  spines  of  the  last  lumbar,  and  lateral  aspect 
of  the  sacral  and  coccygeal  vertebrae. 

Insertion. — The  side  of  the  coccyx,  between  the  erector  and 
depressor. 

Relation. — Superiorly  with  the  erector  and  sacral  ligament; 
inferiorly  with  the  depressor ;  externally  with  the  compressor. 

Action. — To  curve  the  tail,  drawing  it  sideways  over  the 
quarter. 

COMPRESSOR   COCCYGIS. 
(Ischio-coccygeus. ) 

Situated  at  the  side  of  the  pelvis,  it  is  a  large,  thin,  and  tri- 
angular muscle. 

Origin. — By  aponeurosis,  from  the  superior  ischiatic  spine  and 
the  inner  surface  of  the  sacro-sciatic  ligament,  running  upwards 
and  backwards. 

Insertion. — By  fleshy  fibres,  to  the  side  of  the  terminal  sacral 
and  first  two  coccygeal  vertebras. 

Relation. — Externally  with  the  sacro-sciatic  ligament  ;  inter- 
nally with  the  curvator  and  rectum. 

Action. — To  depress  the  entire  tail. 

Muscles  of  the  Limbs. 

The  muscles  of  this  class  are  those  which  are  specially  related 
to  the  limbs,  for  the  most  part  acting  upon  them  alone ;  they  arc 
intrinsic  aud  extrinsic,  according  to  their  origin.      These  muscles 


212  MYOLOGY. 

are  either  flexors^  extensors,  abductors,  adductors,  or  rotators,  but 
in  the  horse  the  last  are  comparatively  few,  limited  in  their 
action,  and  nearly  all  extrinsic,  the  joints  of  the  horse's  limhs 
below  the  shoulder  and  hip  allowing  very  slight  rotatory  motion. 


Muscles  of  the  Pectoral  Limb 
These  may  be  conveniently  divided 

Scapular   , 
Brachial   . 
Antibrachial 
Metacarpal 


nto  the  following  regions  :- 

The  shoulqler. 
The  arm. 
The  fore-arm. 
The  foot  (hand). 


Scapular  Region. 

Externally  the  region  is  covered  by  the  strong  scapular  fascia, 
and  comprises  an  external  group  of  four  and  an  internal  of  three 
muscles. 

External  Scapular  Group. 

Teres  externus.  f  Postea-spinatus. 

Antea-spinatus.  I  Postea-spinatus  minor. 

TERES    EXTERNUS. 

(Scapulo-humeralis  Magnus.) 

(Fig.  78.  c.) 

This  is  the  long  abductor  of  the  arm,  which  corresponds  to 
the  deltoid  of  man.  Situated  on  the  outer  and  posterior  part 
of  the  shoulder,  it  consists  of  two  portions,  anterior  and  posterior. 
The  posterior  or  larger  portion  is  triangular  in  form,  and  very 
fleshy,  the  fibres  extending  obliquely  downwards  and  forwards;  it 
is  lodged  in  a  depression  in  the  caput  magnum.  The  anterior 
or  superior  portion  is  thin,  and  aponeurotic  above,  extending 
over  the  postea-spinatus  muscle,  to  which  it  is  adherent. 

Attachments. — The  posterior  section  arises  from  the  dorsal 
angle  and  posterior  costa  of  the  scapula  ;  the  anterior  by  strong 
fascia  from  a  tubercle  on  the  spine  of  the  scapula,  and  the 
scapular  fascia.  They  unite  inferiorly,  and  by  tendinous  and 
fleshy  fibres  are  inserted  to  the  deltoid  ridge  of  the  humerus 
below  the  insertion  of  the  postea-spinatus  minor. 


EXTERNAL  SCAPULAR  GROUP. 


213 


Jielat  ion.  — Anteriorly 
Avtth  the  ca^put  magnum, 
caput  medium.and  postea- 
spinatus;  externally  with 
the  scapular  fascia, 

A  dion .  —  To  abduct 
the  humerus,  and  rotate 
it  outwards;  when  acting 
with  the  teres  internus 
to  flex  the  shoulder  joint. 


with    the    postea-spinatus  ;    internally 


ANTEA-SPINATUS. 

XSaperacromio-trochiterius.) 

(Fig.  78,  a.) 

Occupying  the  antea- 
?pinatus  fossa  of  the 
scapula,  this  muscle  is 
pjTamidal  in  shape,  with 
the  base  downwards.  Its 
fleshy  fibres  extend  ob- 
liquely forwards;  then  be- 
coming tendinous  infer- 
iorly,  it  is  bifurcated  for 
the  passage  of  the  flexor 
brachii  tendon,  the  divi- 
sions being  connected  by 
aponeurosis. 

Origin.  —  From  the 
anterior  fossa,  anterior 
costa,  and  cervical  angle 
of  the  scapula,  and  the 
anterior  surface  of  its 
spine. 

Insertion.  —  By  two 
parts,  one  external,  to 
the  summit  of  the  exter-     „    ,     ,  .^      .  •    ,.  ^     .     ,   . 

Muscles  of  the  anterior  limb— external  view,    a,  Antea- 

nal    trochanter,    and    one  splnatos  ;  6,  Postea-spInatus  ;  c,  Teres  extemus  ;  d.  Caput 

intprnal     +n    tliP    «iiTYimit  «>agnum ;  e.  Caput  medium  ;/,  Flexor  brachii ;  jr,  Extensor 

luueiudl,   to    xne    summit  metacarpimagnus;  ft, Extensor metacarpiobUquus:i,Flexor 

of  the  internal  trochanter,  metacarpi  extemus ;  fc.  Extensor  pedis  ;  fc',  Its  tendon  ;  fc" 

n  ,1       1  Fibrous  band  from  the  suspensory  ligament ;  I,  Extensor 

Ot  the  humerus.  suffraginis  =  V,  its  tendon. 


Fig.  78. 


214  MYOLOGY. 

Relation. — Externally  with  the  scapular  faScia;  anteriorly 
with  the  pectoralis  parvus  ;  posteriorly  with  the  scapular  spine 
and  the  anterior  border  of  the  postea-spinatus  ;  internally  with 
the  bone ;  antero-inferiorly  with  the  levator  humeri  and  the 
tendon  of  the  flexor  brachii. 

Action. — To  extend  the  humerus  on  the  scapula,  and  tense 
the  fascia  covering  the  flexor  brachii.  It  serves,  like  the  other- 
scapular  muscles,  as  an  active  ligament  of  the  shoulder  joint. 

POSTEA-SPINATUS. 

{Subacromio-trochiterius. ) 

(Fig.  78.  6.) 

Lodged  in  the  postea-spinatus  fossa,  it  is  broad,  flat,  and' 
triangular,  with  the  apex  below,  to  which  its  fibres  converge  ;  it 
is  fleshy,  with  strong  tendinous  intersections. 

Origin. — From  the  posterior  costa  and  fossa  of  the  scapula, 
the  posterior  border  of  its  spine,  and  the  cartilage  of  prolongation 

Insertion. — By  two  divisions,  one  of  which  goes  to  the  inner 
side  of  the  convexity  of  the  external  humeral  trochanter ;  the 
other,  a  strong  tendon,  passes  over  the  trochanter,  and  is  inserted 
to  a  roughened  ridge  below.  Between  the  tendon  and  convexity 
is  a  synovial  bursa. 

Relation. — Externally  with  the  aponeurosis  of  the  teres  ex- 
ternus  and  with  the  scapular  fascia  ;  anteriorly  with  the  antea- 
spinatus  and  the  scapular  spine  ;  posteriorly  with  the  teres 
extemus;  internally  with  the  scapula,  its  cartilage,  and  the 
postea-spinatus  minor ;  inferiorly  it  contacts  the  capsular  ligament 
of  the  shoulder,  joint. 

Action. — To  abduct  the  humerus,  and  rotate  it  outwards. 


POSTEA-SPINATUS   MINOE. 

(Scapulo-humeralis  Parvus.) 

(Fig.  80.  a  a.) 

Situated  on  the  inside  of  the  teres  extemus,  below  the  postea- 
spinatus,  and  along  the  posterior  border  of  the  scapula,  it  is  long 
and  prismatic  inferiorly,  fleshy,  and  intersected  by  tendon,  and 
is  easily  divided  into  a  large  and  small  portion. 

Origin. — From  the  posterior  border  of  the  scapula,  and  by 


INTERNAL   SCAPULAR   GROUP.  215 

tendinous  slips  from  the  posterior  fossa,  and  a  small  tubercle  on 
the  external  side  of  the  rim  of  the  glenoid  cavity. 

Insertion. — To  the  deltoid  ridge. 

Relation. — Externally  with  the  teres  externus  and  postea- 
spinatus  ;  internally  with  the  caput  magnum,  caput  medium,  and 
capsular  ligament. 

Action. — Like  the  last,  to  abduct,  and  rotate  the  humerus 
outwards. 

Internal  Scapular  Group. 

Subscapularis. 
Teres  internus. 
Scapulo-humeralis  posticus. 

SUBSCAPULARIS. 

(Subscapulo-trochineus. ) 

(Fig.  79.  a.) 

Situated  on  the  inner  side  of  the  shoulder  blade,  occupying 
the  subscapular  fossa,  it  is  fan-shaped,  forming  three  points 
supericriy,  ita  fibres  converging  downwards.  It  is  covered  by 
strong  fascia,  from  which  arises  the  subscapulo-hyoideus. 

Origin. — From  the  whole  of  the  subscapular  fossa. 

Insertion. — To  the  internal  humeral  trochanter, by  a  strong  ten- 
don passing  over  its  summit,  where  there  is  a  small  synovial  bursa. 

Relation. — Externally  with  the  scapula;  internally  with  the 
serratus  magnus  ;  anteriorly  with  the  antea-spinatus,  with  which 
it  blends,  the  two  forming  a  space  through  which  passes  the  pre- 
scapular  artery  ;  posteriorly  with  the  teres  internus. 

Action. — To  adduct  the  arm,  and  perhaps  to  rotate  it  slightly 
inwards. 

TERES   INTERNUS. 

(Teres  Major — Suhscapulo-humeralis. ) 

(Fig.  79.  b.) 

This,  an  adductor  of  the  arm,  is  situated  just  behind  the  sub- 
scapularis, at  the  posterior  border  of  the  scapula ;  it  runs  obliquely 
downwards,  corresponding  to  the  terres  externus.  It  is  elongated, 
wide  in  the  middle,  tapering  at  the  extremities,  its  posterior  edge 
being  thin. 

Origin. — From  the  dorsal  angle  and  posterior  costa  of  the 
scapula. 


216 


MYOLOGY. 


Insertion. — By  a  flat  tendon,  which  joins  that  of  the  latissi- 
mus  dorsi,  to  the  internal  tuberosity  of 
the  humerus,  between  the  tendons  of  in- 
sertion of  the  coraco-humeralis. 

Relation. —  Postero- externally  with 
the  fascia  of  the  latissimus  dorsi  and 
scapulo-ulnaris ;  anteriorly  with  the  sub- 
scapularis ;  internally  with  the  serratus 
magnus;  inferiorly  with  the  coraco- 
humeralis  and  humeralis  obliquus. 

Action. — To  ad  duct,  and  rotate  the 
humerus  inwards ;  acting  with  the  teres 
externus  the  result  is  flexion. 


SCAPULO-HUMERALIS    POSTICUS. 
(Scapulo-humeralis  Gracilis — Grele. ) 

Situated  behind  the  shoulder  joint, 
between  the  caput  magnum  and  the  cap- 
sular ligament,  it  is  very  small,  slender, 
and  fusiform,  with  a  pale,  delicate,  fleshy 
belly,  and  tendinous  extremities. 

Origin.  —  From  the  postero-inferior 
part  of  the  scapula,  just  above  the 
glenoid  cavity,  and  the  capsulaT  ligament 
of  the  shoulder  joint. 

Insertion. — Between  the  fibres  of  the 
humeralis  obliquiis,  to  the  posterior  part 
of  the  humerus,  just  below  its  head. 

Action. — To  render  tense  the  capsular 
ligament  of  the  joint,  and  thus  prevent 
its  being  crushed  during  flexion ;  this 
action  was  ascribed  to  it  by  Rigot,  who 
was  the  first  to  describe  it.  It  is 
believed  to  be  peculiar  to  the  solidun- 
gula. 


Fig.  79. 
Muscles  of  the  anterior  limb- 
internal  view,    a,  Subscapularis; 
b.    Teres    intemus ;    c,    Coraco- 
hnmeralis;   d,    Scapulo-ulnaris; 

e.  Flexor    metacarpi   intemus; 

f.  Flexor  metacarpi  medius;  g, 
.Caput  parvum. 


Brachial  Region. 

This  region  clothed  by  the  brachial  fascia,  includes  the  muscles 
which  cover  the  humerus  and  its  vicinity;   they  consist  of  an. 


ANTERIOR  BRACHIAL  GROUP.  217 

anterior  and  a  posterior  group,  the  former  being  mostly  anterior 
or  lateral  to  the  bone,  the  latter  situated  behind  it,  In  either 
^roup  we  find  three  muscles. 


Anterior  Brachial  Group. 

Flexor  brachii. 
Coraco-humeralis. 
Humeralis  obliquus. 


FLEXOR  BRACHII. 

(Coraco-radialis.) 

(Fig.  78.  /.) 

The  analogue  of  the  biceps  in  man,  this  muscle  is  situated  in 
front  of  the  humerus  :  it  is  long  and  cylindrical,  passing  down- 
wards and  backwards.  The  tendon  of  origin  contains  fibro-cartilage, 
and  the  belly  is  intersected  by  tendinous  fibres. 

Origin. — From  the  base  of  the  coracoid  process  of  the  scapula, 
l)y  a  strong  tendon,  which  passes  over  the  bicipital  groove  where 
there  is  a  synovial  bursa. 

InseHion. — By  a  short  tendon  to  the  bicipital  tuberosity  on 
the  antero-internal  part  of  the  head  of  the  radius,  and  to  the 
capsular  ligament  of  the  elbow  joint ;  a  part  of  it  passes  under 
the  internal-lateral  ligament  of  the  elbow  joint.  A  strong  fibrous 
band  is  given  off  inferiorly  which  joins  and  expands  over  the 
extensor  metacarpi  magnus,  and  becomes  blended  with  the  anti- 
trachial  fascia. 

Relation.  —  Anteriorly  with  fascia,  covered  by  the  levator 
humeri  ;  internally  with  the  coraco-humeralis;  posteriorly  with 
the  humerus;  superiorly  its  tendon  passes  between  the  two 
insertions  of  the  antea-spinatus,  where  a  strong  fascia  envelopes 
it  and  is  tensed  by  the  last-named  muscle. 

Action. — To  flex  the  radius  on  the  humerus,  extend  the  latter 
on  the  scapula,  and  to  tense  the  antibrachial  fascia.  A  band 
of  unyielding  tendinous  material  runs  through  this  muscle, 
enabling  it  to  act  as  a  ligament,  and  passively  support  the 
shoulder  joint,  when  the  animal  is  at  rest ;  the  band  joining  the 
extensor  metacarpi  also  relieves  muscular  tension. 


218  MYOLOGY. 


CORACO-HUMERALIS. 

Omo-hrachialis. 
(Fig.  79.  c.) 

Situated  on  the  inner  side  of  the  humerus,  this  muscle  is  ten- 
dinous, long,  and  fusiform,  its  fibres  passing  obliquely  downwards. 

Attachments. — From  the  beak  of  the  coracoid  process  of  the 
scapiila.  Passing  between  the  subscapularis  and  the  antea- 
spinatus,  the  tendon  is  succeeded  by  two  fleshy  bellies,  a  super- 
ficial and  a  deep  one.  The  latter,  thin  and  short,  is  inserted  to 
the  shaft  of  the  humerus  just  above  its  internal  tuberosity  ;  the 
former,  by  far  the  larger,  is  inserted  to  a  rough  surface  on  the 
same  bone,  lower  down,  and  more  anteriorly. 

Relation. — Anteriorly  with  the  flexor  brachii ;  superiorly  with 
the  antea-spinatus  and  subscapularis  ;  internally  with  the  pector- 
alis  magnus ;  posteriorly  with  the  latissimus  dorsi  and  teres 
internus,  whose  tendons  pass  between  its  two  bellies. 

Action. — To  extend,  adduct,  and  rotate  the  arm  inwards. 

HUMERALIS    OBLIQUUS. 

{Humero-radialis — Brachialis  A nticus. ) 

(Fig.  80.  d.) 

Occupying  the  musculo-spiral  groove,  it  is  flat,  oblong,  wide 
superiorly,  and  almost  entirely  fleshy ;  it  covers  successively 
portions  of  the  posterior,  external,  and  anterior  surfaces  of  the 
humerus,  terminating  on  the  inner  aspect  of  the  radius. 

Origin. — From  the  postero-superior  part  of  the  shaft  of  the 
humerus,  just  below  the  articular  head,  winding  round  the  bone 
under  the  external  tuberosity. 

Insertion. — To  a  ridge  on  the  inner  part  of  the  head  of  the' 
radius,  after  passing  through  a  transverse  groove  just  below,  and 
within  the  insertion  of  the  flexor  brachii ;  also  to  the  ulna,  passing 
imder  the  internal-lateral  ligament  of  the  joint,  and  blending  with 
the  arciform  ligament. 

Relation. — Externally  with  the  caput  magnum  and  caput 
medium ;  internally  with  the  humerus  ;  anteriorly  with  the  flexor 
brachii. 

Action. — Solely  to  flex  the  elbow  joint. 


POSTERIOR  BRACHIAL   GROUP.  219 


Posterior  Brachial  Group 


Scapulo-ulnaris. 
Triceps  extensor  brachii. 
Anconeus. 


scapulo-ulnaris. 

{Scapulo-olecranius  Longus.) 
(Fig.  79.  d.) 


Situated  on  the  postero-internal  aspect  of  the  region,  adhering 
to  the  caput  magnum,  this  is  a  broad  and  flat  muscle,  aponeurotic 
at  its  origin,  with  a  fleshy  belly,  and  divisible  into  an  anterior 
and  posterior  portion. 

Origin. — Aponeurotic,  from  the  dorsal  angle  and  posterior 
costa  of  the  scapula. 

Insertion. — To  the  inner  part  of  the  apex  of  the  olecranon, 
and  to  the  antibrachial  fascia. 

Relation. — Externally  with  the  caput  magnum;  anteriorly 
with  the  caput  medium  ;  internally  with  the  pectoralis  magnus ; 
superiorly  with  the  latissimus  dorsi. 

Action. — To  flex  the  shoulder  joint,  extend  the  elbow  joint, 
and  tense  the  antibrachial  fascia. 


triceps  extensor  brachu. 

{Triceps  Brachii.) 

(Fig.  78.  d,  e.) 

A  very  large  and  powerful  muscle,  occupying  the  space  between 
the  posterior  border  of  the  scapula,  the  humerus,  and  the 
olecranon.  It  consists  of  three  parts,  which  have  different  origins, 
but  a  common  insertion  to  the  olecranon  process.  We  describe 
them  as  if  they  were  separate  muscles,  under  their  respective 

Caput  magnum. 
Caput  medium. 
Caput  parvum. 


220  MYOLOGY. 


CAPUT  MAGNUM. 

{Scnpulo-olecranius  Magnus.) 
(Fig.  78.  d.) 

This,  the  great  extensor  of  the  fore-arm,  is  situated  on  the 
posterior  aspect  of  the  shoulder.  It  is  thick  and  triangular, 
extending  obliquely  downwards  and  backwards,  and  consists  of 
several  bundles,  with  tendinous  intersections. 

Origiv. — From  the  dorsal  angle  and  posterior  costa  of  the 
scapula. 

Insertion. — By  a  strong  tendon  to  the  inner  and  upper  part  of 
the  olecranon,  a  synovial  bursa  being  interposed  between  it  and 
the  apex.      It  receives  many  fibres  from  the  caput  medium. 

Relation. — Externally  with  the  fascia,  the  panniculus  carnosus,, 
and  the  teres  externus,  which  occupies  a  depression  in  it ;  inter- 
nally with  the  latissimus  dorsi,  scapulo-ulnaris,  and  teres  internus; 
inferiorly  with  the  caput  medium  and  caput  parvum. 

Action. — To  flex  the  shoulder  joint,  and  extend  the  fore-arm. 


CAPUT  MEDIUM. 

(Ihimei'o-olecranius  ExtermLS.") 
(Fig.  78.  e.) 

Placed  between  the  preceding  niuscle  and  the  humerus,  it  is 
thick,  short,  and  fleshy,  extending  obliquely  backwards  and  down- 
wards. 

Origin. — Aponeurotic,  from  a  ridge  on  the  supero-posterior 
part  of  the  shaft,  of  the  humerus,  running  from  the  deltoid  ridge 
to  the  neck. 

Insertion. — The  supero-posterior  part  of  the  olecranon ;  or  it 
may  join  the  tendon  of  the  caput  magnum. 

Relation. — Superiorly  with  the  caput  magnum ;  externally 
with  the  teres  externus ;  inferiorly  with  the  humeralis  obliquus 
and  extensor  metacarpi  magnus;  internally  with  the  caput  parvum. 

Action. — To  extend  the  fore-arm. 


ANTIBRACHIAL  REGION.  221 

CAPUT  PARVUM. 

(Bumero-olecranius  Internus.) 
(Fig.  81.  a.) 

Placed  on  the  inner  and  mesiau  portion  of  the  shaft  of  the 
humerus,  along  the  inferior  border  of  the  caput  magnum,  this 
muscle  is  slender  and  triangular,  with  a  fleshy  origin.  The  fibres 
pass  obliquely  backwards  and  downwards,  terminating  in  two  flat 
tendons. 

Origin. — From  the  postero-internal  part  of  the  middle  third 
of  the  humerus,  extending  from  the  inner  tubercle. 

Insertion. — To  the  inner  part  of  the  apex  of  the  olecranon, 
one  tendon  passing  over  a  small  groove  before  its  insertion,  Avhich 
is  situated  below  the  other  one. 

Relation. — Superiorly  '  with  the  caput  magnum ;  externally 
with  the  humerus,  humeralis  obliquus,  and  caput  medium  ;  in- 
ternally with  the  insertion  of  the  coraco-humeralis,  with  the  teres 
internus,  latissimus  dorsi,  and  scapulo-ulnaris. 

Action. — To  extend  the  fore-arm. 


ANCONEUS. 

{Humero-olecranius  Parvus.) 

(Fig.  80.  e.) 

Situated  at  the  back  of  the  elbow  joint,  it  is  small,  thick,  and 
almost  entirely  fleshy,  filling  up  the  space  between  the  condyles 
of  the  humerus,  or  the  olecranon  fossa. 

Origin. — From  the  borders  of  the  fossa,  chiefly  the  epi trochlea, 
and  the  capsular  ligament  of  the  elbow  joint. 

Insertion. — The  antero-extemal  part  of  the  olecranon. 

Relation. — Posteriorly  with  the  caput  medium  muscle ;  ante- 
riorly with  the  elbow  joint  and  humerus. 

Action. — To  tense  the  capsular  ligament,  and  prevent  it  from 
being  crushed  during  extreme  extension. 

ANTIBRACHIAL  REGION. 

The  muscles  of  this  region,  the  fore-arm,  cover  the  ulna  and 
radius,  except  on  the  inner  aspect  of  the  latter,  where  there  is  little 
interposed  between  the  skin  and  the  bone  ;  they  are  divided  into 


222  MYOLOGY. 

two  distinct  groups,  tlie  anterior  and  posterior,  tlie  first  of  wliich 
are  all  extensors,  the  second  all  flexors.  All  these  muscles  are 
inserted  below  the  radius,  and  therefore  act  upon  the  carpus 
or  on  the  joints  below.  The  region  is  enclosed  in  the  antibrachial 
fascia,  an  exceedingly  strong  covering,  which  is  firmly  attached 
to  the  radius  and  ulna. 


Anterior  Antibrachial  Group. 

extensors. 

The  extensor  group  includes  four  muscles  : — 

Extensor  metacarpi  magnua.     ]         Extensor  pedis. 
Extensor  metacarpi  obliquus.    |         Extensor  suflfraginis. 

EXTENSOR   METACARPI   MAGNUS. 

(Epicondylo-premeiacarpeus. ) 

(Fig.  78.  g.) 

Situated  in  front  of  the  radius,  and  in  figure  pyramidal,  extend- 
ing downwards,  it  consists  of  a  fleshy  belly,  and  a  long  flat  tendon, 
which  commences  at  about  the  lower  third  of  the  radius,  and  passes 
over  the  carpus,  terminating  at  the  head  of  the  meta.carpus. 

Origin. — From  the  epitrochlea,  or  ridge  above  the  external 
condyle  of  the  humerus,  from  the  capsular  ligament  of  the  elbow 
joint  anteriorly,  and  the  surface  just  above.  It  receives  a  strong 
tendinous  band  from  the  flexor  brachii.  The  tendon  passes 
through  a  groove  or  theca  in  the  anterior  part  of  the  distal  end  of 
the  radius,  where  there  is  a  synovial  sheath  or  bursa,  then  over 
the  knee  through  a  second  synovial  apparatus.  Two  synovial 
sheaths  are  thus  interposed  betv/een  the  bones  and  the  tendon, 
the  latter  being  bound  down  by  the  anterior  annular  ligaments, 
and  by  the  tendon  of  the  extensor  metacarpi  obliquus,  which 
crosses  it  in  an  oblique  manner  just  above  the  carpus. 

Insertion. — To  a  tuberosity^  on  the  anterior  part  of  the  head  • 
of  the  great  metacarpal  bone,  towards  its  inner  side. 

Relation. — Anteriorly  with  the  fascia ;  posteriorly  with  the 
radius  ;  externally  with  the  extensor  pedis ;  supero-internally  with 
the  humeralis  obliquus  and  flexor  brachii ;  inferiorly  with  the 
extensor  obliquus. 

Action. — To  extend  the  carpus. 


ANTERIOR  ANTIBRACHIAL  GROUP. 


223 


EXTENSOR   METACAEPI   OBLTQUUS. 

(Badio-premetOfCarpeus. ) 

(Fig.  78.  h.) 

This  muscle  is  situated  on  the  infero- 
anterior  part  of  the  radius,  and  is  tri- 
angular and  penniform  ;  aponeurotic 
above,  it  terminates  in  a  small  tendon, 
which  crosses  obliquely  the  inferior 
extremity  of  the  anterior  surface  of 
the  radius,  under  the  extensor  pedis, 
and  over  the  extensor  metacarpi 
magnus  tendon. 

Origin. — From  the  external  border 
of  the  radius.  Its  tendon  passes 
through  the  oblique  groove  on  the 
antero-internal  part  of  the  distal  end 
of  the  radius,  where  there  is  a  synovial 
sheath. 

Insertion. — The  head  of  the  inner 
metacarpal  bone. 

Relation. — Anteriorly  with  the  ex- 
tensor pedis  and  the  fascia ;  posterior- 
ly with  the  extensor  metacarpi  magnus 
and  the  bone. 

Action. — To  extend  the  metacar- 
pus, and  rotate  it  slightly,  carrying 
the  inner  aspect  forwards. 


EXTENSOR   PEDIS. 

(Bpitrochleo-prephalangeus. ) 

(Fig.  78.  Jc;  Fig.  80./.) 

Placed  on  the  antero-external  part 
of  the  fore-arm,  it  is  long  and  pyra- 
midal, extending  downwards  ;  fleshy 
above,  its  belly  is  bifid  inferiorly,  and 
terminates  in  a  long  tendon,  which  is 
double,  and  commences  about  the 
inferior  third  of  the  radius. 


Fig.  80. 

External  view  of  the  muscles  of  the 
anterior  limb— showing  the  deeper 
ones  of  the  upper  region,  aa,  Postea- 
spinatus  minor ;  b,  Deep  portiop  of 
postea-spinatus ;  c,  Flexor  brachii 
divided,  and  the  upper  part  raised  ; 
c'.  Its  tendon,  which  fits  the  bicipital 
groove ;  d,  Humeralis  obliquus ;  e,  An- 
coneus ;  /,  Extensor  pedis ;  g,  Thier- 
nesse's  muscle  ;  h,  Phillips'  muscle ; 
h'.  Its  tendon. 


224  MYOLOGY. 

Origin. — The  fleshy  part  arises  from  the  base  of  the  epitrochlea^ 
and  the  anterior  border  of  the  external  lateral  ligament  of  the 
elbow  joint,  the  front  of  the  distal  extremity  of  the  humerus,  and 
the  outer  part  of  the  head  of  the  radius.  The  tendon,  which  is 
double,  passes  through  a  synovial  theca  in  the  external  groove  on 
the  distal  end  of  the  radius,  under  the  anterior  annular  ligament. 
Below  the  knee  it  sends  a  small  tendon  to  join  that  of  the 
extensor  suffraginis  ;  then  expanding,  it  passes  over  the  front  of 
the  fetlock  joint,  being  attached  to  the  capsular  ligament,  and 
having  a  small  synovial  bursa  interposed ;  below  the  fetlock  it 
receives  on  either  side  a  strong  slip  from  the  suspensory  ligament, 
and  it  becomes  attached  to  the  anterior  part  of  the  first  and 
second  phalanges. 

Insertion. — To  the  pyramidal  process  of  the  os  pedis. 

Relation. — Anteriorly  and  externally  it  is  covered  by  the 
fascia  ;  posteriorly  related  with  the  extensor  suffraginis,  the 
radius,  carpus,  metacarpus,  and  phalanges ;  internally  with  the 
extensor  metacarpi  magnus. 

Action. — To  extend  the  phalanges  on  each  other,  and  assist 
in  extending  the  carpus. 

If  the  tendon  which  joins  that  of  the  extensor  suffraginis  be 
carefully  traced  upwards,  it  will  be  found  to  be  continuous  with 
a  long  thin  muscle  separable  from  the  extensor  pedis,  and  placed 
along  its  postero-extemal  aspect ;  it  arises  from  the  external 
lateral  ligament  of  the  elbow  joint  and  the  corresponding  tuber- 
osity pf  the  radius,  and  has  received  the  name  of  Phillips'  muscle 
(Fig.  80.  h).  Somewhat  anteriorly  to  the  above  a  still  smaller 
muscle  may  be  found  arising  from  the  external  arciform  ligament, 
and  terminating  in  a  small  tendon,  which  joins  that  of  the 
extensor  pedis  a  short  distance  above  the  carpus ;  this  has  been 
called  Thiernesse's  muscle  (Fig.  80.  g).  These  two  muscles  are 
not  generally  described,  but  are  regarded  as  forming  a  part  of 
the  extensor  pedis. 

EXTENSOR   SUFFRAGINIS. 

(Eadio-prephalangetis.) 

(Fig.  78. 1.) 

Situated  on  the  external  part  of  the  fore-arm,  between  th» 

extensor  pedis  and  the  flexor  metacarpi  externus,  this  muscle  is 

semipenniform,  consisting  of  a  flattened  fleshy  belly,  enveloped  in 


POSTERIOR    ANTIBRACHIAL    GROUP  225 

a  strong  aponeurotic  sheatb,  and  having  its  edge  turned  outwards. 
The  belly  ends  in  a  round  tendon,  which  passes  through  a  theca 
in  the  vertical  groove  on  the  external  side  of  the  distal  end  of 
the  radius,  and  down  the  external  aspect  of  the  carpus,  reaching 
the  anterior  surface  of  the  large  metacarpal  boue. 

Origin. — From  the  external  part  of  the  head  of  the  radius, 
the  external  lateral  ligament  of  the  elbow  joint,  the  shaft  of  the 
radius,  and  the  lateral  aspect  of  the  ulna. 

Insertion. — To  the  head  of  the  os  sufifraginis,  related  also  with 
the  capsular  ligament  of  the  fetlock  joint.  Below  the  knee  it  is 
joined  by  two  tendinous  slips,  one  from  the  tendon  of  the  extensor 
pedis,  the  other,  a  species  of  check  ligament,  from  the  trapezium. 

Relation. — Anteriorly  with  the  extensor  pedis  ;  posteriorl}* 
with  the  flexor  pedis  perforatus,  the  perforans,  and  flexor  meta-- 
carpi  externus  ;  externally  with  the  fascia. 

Action. — To  extend  the  digit,  and  assist  the  extensor  pedis. 

Posterior  Antibrachial  Group. 

FLEXORS. 

This,  the  flexor  group,  consists  of  seven  muscles,  three  flexors 
of  the  carpus,  and  four  flexors  of  the  digit :  — 


Flexor  metacarpi  externus. 
Flexor  metacarpi  medius. 
Flexor  metacarpi  internus. 


Flexor  pedis  perforatus. 
Flexor  pedis  perforans 
Ulnaris  accessorius. 


Radialis  accessorius. 

FLEXOR  METACARPI  EXTERNUS. 

(JUpitrochleo-carpeus. ) 

(Fig.  78.  i.) 

Situated  on  the  postero-external  aspect  of  the  fore-arm,  this 
muscle  is  elongated  and  flattened,  the  fleshy  belly  being  inter- 
sected by  strong,  tendon. 

Origin. — By  a  very  short  strong  tendon  from  the  summit  of 
the  epitrochlea  of  the  humerus,  terminating  in  two  tendons ;  the 
anterior,  longer,  and  more  delicate,  passes  through  a  synovial 
theca,  in  a  groove  on  the  external  surface  of  the  trapezium. 

Insertion. — The  anterior  tendon  goes  to  the  head  of  the  outer 
splint  bone ;  the  posterior,  short  and  flat,  becomes  inserted  to  the 

Q 


226  MYOLOGY. 

superior  part  of  the  trapezium,  blending  with  the  flexor  meta- 
carpi  medius. 

Relation. — Externally  with  the  fascia  ;  internally  with  the 
flexor  pedis  muscles  and  the  flexor  medius ;  anteriorly  with  the 
extensor  suffraginis. 

Action. — To  flex  the  carpus. 

FLEXOR    METACARPI    MEDIUS. 

(Flexor  M.  Obliquus — Epicondylo-carpeus.) 

(Fig.  79./.) 

Similar  in  structure  to  the  preceding  muscle,  it  is  situated  on 
the  postero-internal  part  of  the  radius,  extending  downwards  and 
outwards.  It  is  long,  flat,  and  bifid  above  ;  one  head  is  small, 
the  other  large  and  fleshy. 

Origin. — The  large  head  arises  from  the  epicondyle,  the  small 
Tiead  from  the  posterior  surface  of  the  olecranon  ;  they  unite  at  a 
short  distance  down  the  radius. 

Insertion. — By  one  tendon  to  the  supero-posterior  and  inter- 
nal part  of  the  trapezium,  blending  with  the  extemus. 

Relation. — Externally  with  the  fascia ;  internally  with  the 
flexors  bf  the  foot ;  anteriorly  with  the  flexor  intemus  ;  posteriorly 
with  the  flexor  externus. 

Action. — To  assist  the  preceding  muscle  in  flexing  the  carpus. 

FLEXOR    METACARPI    INTERNUS. 

{Epicondylo-metacarpeus. ) 

(Fig.  79.  e.) 

'Situated  on  the  internal  aspect  of  the  fore-arm,  it  resembles 
'the  two  preceding  muscles  in  its  structure,  being  long  and 
flattened,  with  a  fleshy  belly,  but  having  a  long  tendon  of 
insertion. 

Origin. — By  tendinous  fibres  from  the  base  of  the  epicondyle 
just  by  the  medius. 

InseHion. — To  the  head  of  the  inner  splint  bone,  the  long 
round  tendon  passing  through  a  synovial  theca  on  the  inner  side 
of  the  carpus. 

Relation. — Externally  with  the  fascia  ;  internally  with  the 
chief  radial  vessels  and  nerves,  and  the  flexors  of  the  foot  ; 
anteriorly  with  the  radius  ;  posteriorly  with  the  medius. 

Action. — Like  the  preceding,  to  flex  the  carpus. 


POSTERIOR    ANTIBRACHIAL    GROUP. 


9.-27 


FLEXOR    PEDIS   PERFORATUS. 

{Flexor  Sahlimis — Epicondylo-phalangeus. ) 

(Fig.  81.  h.) 

Situated  in  the  posterior  region  of  the 
fore-arm,  under  the  flexors  of  the  carpus, 
this  muscle  is  -long,  thin,  and  prismatic, 
its  belly  being  fleshy,  with  tendinous 
intersections,  and  extending  almost  to  the 
carpus,  where  it  is  succeeded  by  a  long 
tendon,  which  passes  through  a  synovial 
sheath  behind  the  joint,  closed  in  by  the 
posterior  annular  ligament.  Above  the 
carpus,  the  tendon  is  joined  by  a  broad 
band  of  fibrous  tissue,  called  the  superior 
carpal  or  superior  "  check "  ligament, 
which  springs  from  the  infero-posterior 
surface  of  the  radius,  being  also  attached 
to  the  antibrachial  fascia,  and  usually  to 
the  perforans  muscle ;  below  the  knee, 
the  tendon  assists  in  the  formation  of  a 
synovial  sheath  for  the  tendon  of  the 
flexor  perforans.  At  the  fetlock  it  ex- 
pands and  forms  a  ring  or  sheath,  through 
which  passes  the  perforans  tendon,  hence 
the  names  perforans  and  perforatus;  below 
the  pastern  joint  the  tendon  divides  into 
two. 

Origin. — From  the  summit  of  the  epi- 
condyle,  by  a  tendon  common  to  it  and 
the  perforans. 

Insertion. — To  the  projecting  lateral 
parts  of  the  os  corona?. 

Relation. — Posteriorly  with  the  flexor 
metacarpi  externus  and  medius ;  anteri- 
orly with  the  perforans.  Two  important 
synovial  sheaths  or  canals  are  related 
with  this  and  the  perforans  tendon, 
the  carpal  and  the  metacarpo-phalangeal.  The  first,  to  which 
is  attached  the   antibrachial    fascia,   is  formed    by  the  posterior 


Fio.  81. 

Internal  view  of  the  deep  muscles 
of  the  anterior  limb,  a,  Caput  par-, 
vum  of  triceps  extensor  brachii  ; 
&,  Flexor  pedis  perforatus ;  6',  Its 
tendon  ;  6"  V",  Slips  to  the  phal- 
anges ;  c  c,  Flexor  pedis  perforans  ; 
c',  Radialis  accessorius  ;  c",  Ulnaris 
accessorius  ;  c'",  Inferior  check  liga- 
ment ;  d,  Perforans  tendon  leaving 
the  sheath  of  oerforatus  tendon. 


228  MYOLOGY. 

carpal  and  annular  ligaments  ;  the  second  is  formed  by  the  car- 
tilaginous pad  clothing  the  great  sesamoid  bones,  the  posterior 
face  of  their'  inferior,  and  their  annular  ligaments,  the  latter 
being  very, adherent  to  the  perforatus  tendon,  which  it  covers, 
and  is  continued  both  upwards  and  downwards,  being  attached 
to  the  phalanges  by  three  fibrous  bands  on  each  side.  The 
synovial  membranes  lining  these  sheaths,  and  reflected  on  the 
tendons,  are  very  large,  and  project  considerably  above  and 
below,  each  forming  an  upper  and  a  lower  cul-de-sac ;  the  lower 
one  of  the  sesamoidean  sheath  reaching  that  formed  by  the  mem- 
brane of  the  coffin  joint,  and  also  the  superior  one  of  the  navicular 
sheath. 

Action. — To  flex  the  pastern  and  fetlock  joints,  and  assist  in 
flexing  the  carpus.  The  superior  check  ligament  enables  it  to  act 
as  an  unyielding  brace  to  the  joints  below  during  rest. 

FLEXOR    PEDIS    PERFOEANS. 

{Flexor-Profundus — Ejncondylo-phalangeus. ) 
(YiG.  81.  c  c.) 

This  muscle  is  situated  between  the  preceding  one  and  the 
radius ;  it  is  long,  tendinous  at  its  origin,  with  a  round  fleshy 
belly,  much  larger  than  that  of  the  perforatus,  and  ending,  above 
the  carpus,  in  a  funicular  tendon.  This  tendon  passes  through 
the  posterior  carpal  sheath,  then  through  a  sheath  partly  formed 
by  the  perforatus  tendon  below;  it  is  joined  by  the  tendons  of 
the  accessory  flexors,  and  half-way  down  the  metacarpus  by  the 
inferior  carpal  or  check  ligament,  a  strong  fibrous  band  which 
is  continuous 'with  the  posterior  carpal  ligamemt.  The  tendon 
then  passes  through  the  sesamoidean  sheath  anteriorly  to  the  per- 
foratus tendon,  and  then  between  the  terminal  slips  of  the  latter, 
over  the  supero-posterior  part  of  the  os  coronse,  when  it  expands, 
the  expanded  part  being  termed  the  plantar  aponeurosis;  it  passes 
thence  over  the  navicular  bone,  and  its  synovial  capsule,  to  the 
solar  aspect  of  the  pedal  bone. 

Origin. — In  common  with  the  perforatus  from  the  epicondyle. 

Insertion. — To  the  semilunar  ridge  on  the  solar  aspect  of  the 
OS  pedis. 

Relation. — Posteriorly  with  the  perforatus;  anteriorly  with 
the  radialis  accessorius  and  the  radius.  Connected  with  the 
terminal  portion  of  the  tendon,  we  may  remark  that  the  synovial 


POSTERIOR    ANTIBRACHIAL    GROUP. 


229 


capsule  of  the  navicular  bone,  termed  the  navicular  sheath,  forms 
two  ciil-de-mcs,  one  stretching  upwards  almost  to  the  inferior 
cul-de-sac  of  the  sesamoid  sheath,  the  other  being  situated  under 
the  inferior  navicular  ligament.  A  broad  strengthening  sheath  of 
fibrous  tissue  covers  the  plantar  aponeurosis  and  blends  with  it 
inferiorly,  being  attached  above  by  two  bands  to  the  sides  of  the 
first  phalanx. 

Action. — It  flexes  the  joints  below  the  carpus,  and  assists  in 
flexiugr  the  latter. 


FtG.  S2. 
Longitudinal  section  through  the  digit  of  a  Horse. 
1,  The  skin  ;  2,  Extensor  pedis  tendon  ;  3,  Synovial  cap- 
sule of  pastern  joint;  i,  Metacarpus;  5,  Perforatus 
tendon  ;  6  (omitted  In  cut),  Perforans  tendon  ;  7,  Synovial 
sheath  ;  8,  Projecting  synovial  cul-de-sac;  9,  Inner  aspect 
of  sesamoid  bone  ;  10,  The  fetlock  ;  11,  The  Y-ligament ; 
12,  The  V-ligament ;  13,  Proximal  phalanx  ;  14,  Terminal 
portion  of  extensor  tendon;  15,  Mesian  phalanx;  16, 
Third  sesamoid  or  navicular  bone  ;  17,  The  sensitive  frog  ; 
18,  Distal  phalanx  ;  19,  The  hoof ;  20,  Sensitive  laminse. 


ULNARIS    ACCESSORIUS. 

{Flexor  Accessorius  Suhlimis.) 

(Fig.  81.  c".) 

Situated  on  the  posterior  part  of  the  fore-arm,  between  the 
external  and  middle  flexors  of  the  metacarpus,  it  is  triangular. 


230  MYOLOGY. 

passing  obliquely  downwards  and  inwards ;  it  has  a  short,  thick, 
fleshy  belly,  ending  in  a  long,  slender,  flat  tendon. 

OHgin. — From  the  posterior  border  and  summit  of  the  ole^ 
cranon. 

Insertion. — It  blends  with,  and  helps  to  form  the  tendon  of 
the  perforans  near  the  carpus. 

Relation. — Superiorly  with  the  fascia ;  internally  with  the 
flexor  metacarpi  internus ;  externally  with  the  medius. 

Action. — It  assists  the  flexor  perforans. 

RADIALIS    ACCESSORIUS. 

{Flexor  Accessorius  Profundus.) 

(Fig.  81.  c'.) 

A  small  muscle  situated  on  the  postero- inferior  part  of  the- 
radius.  Somewhat  radiating,  flat,  and  elongated,  passing  down- 
wards and  slightly  inwards,  it  ends  above  the  knee  in  a  slender 
tendon. 

Origin. — From  the  posterior  part  of  the  shaft  of  the  radius. 

Insertion. — It  joins  the  tendon  of  the  perforans. 

Relation. — Anteriorly  with  the  radius  ;  posteriorly  with  th& 
perforatus  and  perforans. 

Action. — To  assist  the  flexor  perforans. 

Metacarpal  Eegion. 

Below  the  carpus  we  find  only  two  pairs  of  exceedingly  small 
muscles : — 

Interossei  metacarpei. 
Lumbricales. 

INTEROSSEI   METACARPEI. 
(Interossei  Palmares,  Human.) 

Situated  on  the  inside  of  the  small  metacarpal  bones,  these 
muscles  each  consist  of  a  thin,  fleshy  belly,  and  a  long,  slender 
tendon,  which  sometimes  joins  the  band  extending  from  the 
suspensory  ligament  to  the  extensor  tendon,  or  may  join  the 
tendon  itself.  These  muscles  belong  to  the  rudimentary  small 
metacarpal  bones,  and  hence  are  themselves  rudimentary  ;  the 
interosseus  of  the  middle  bone  is  usually  considered  as  being 
represented  by  the  suspensory  ligament 


GLUTEAL    REGION.  231 

LUMBRICALES. 

(^Litmbrici.) 

These  small  muscles  originate  on  either  side  of  the  perforans, 
and  the  sesamoidean  ring  of  the  perforatus  tendons  ;  they  termi- 
nate in  their  tendons,  which  become  lost  in  the  coverings  of  the 
fetlock  joint. 

Muscles  of  the  Pelvic  Limb. 

The  movements  caused  by  these  muscles  resemble  those  of  the 
anterior  limb.  It  should,  however,  be  borne  in  mind  that  the 
stifle  joint  allows  more  extensive  and  varied  motion  than  the 
elbow,  while  the  motion  in  the  tarsus  is  less  free  than  that  in 
the  carpus,  the  former  being  in  effect  purely  ginglymoid  ;  also 
that  the  posterior  is  capable  of  more  extensive  abduction  at  the 
hip  joint  than  is  the  anterior  limb  at  the  shoulder,  although  the 
former  is  more  bound  by  ligaments.  The  muscles  of  the  liinb 
in  question  may  be  divided  into  those  associated  with  the  follow- 
ing regions  : — 

Gluteal The  hip. 

Femoral The  thigh. 

Tibial '.  The  leg. 

Metatarsal The  foot. 

Gluteal  Region. 

The  muscles  of  this  region,  called  also  the  hip  or  the  croup, 
arise  externally  or  internally  from  the  pelvis,  the  sacrum,  and 
the  sacro-sciatic  ligament,  and  are  all  attached  to  the  femur  near 
its  proximal  end,  being  related  with  the  hip  joint.  Collectively 
the  muscles  from  which  this  region  is  named  form  in  the  horse 
an  enormous  fleshy  mass,  apparent  in  the  living  animal  as 
a  rounded  prominence,  behind  and  above  the  anterior  iliac 
spine,  to  which,  and  to  the  sacral  spine,  the  strong  gluteal 
fascia  which  invests  them  is  firmly  attached  ;  a  thin  layer  of 
fat  is  generally  found  covering  the  region  superiorly.  In  this 
region  we  have  one  group  containing  nine  muscles,  named  as 
follows  : — 


232  MYOLOGY. 


Gluteus  externus. 
Gluteus  maxim  us. 
Gluteus  internus. 
Rectus  parvus. 


Obturator  externus. 
Obturator  internus. 
Pyriformis. 
Gemellus  anticus. 
Gemellus  posticus. 


GLUTEUS  EXTERNUS. 

{Ilio-trochanterius  Medius.) 

(Pl.  IL  56;  Fig.  84.  h.) 

This  is  a  V-shaped  muscle  situated  on  the  external  part  of  the 
croup,  its  fibres  converging  downwards.  It  consists  of  a  muscular 
and  an  aponeurotic  portion ;  the  former  is  double,  the  parts  con- 
verging and  ending  in  a  flat  tendon  ;  the  aponeurotic  joins  the 
fleshy  portion  posteriorh^  and  is  hidden  under  the  triceps  abduc- 
tor femoris. 

Origin. — The  anterior  portion  arises  from  the  anterior  spine 
of  the  ilium,  the  pocterior  from  the  second  and  third  sacral 
spines ;  also  from  the  gluteal  fascia. 

Insertion. — To  the  trochanter  minor;  the  aponeurotic  portion 
reaches  the  tuberosity  of  the  ischium  and  the  sacro-sciatic  liga- 
ment. 

Relation. — Externally  with  the  gluteal  fascia  ;  anteriorly  with 
the  fascia  lata  ;  posteriorly  with  the  triceps  abductor ;  internally 
with  the  maxim  us, 

Aotion. — It  abducts  the  thigh. 

GLUTEUS   MAXIMUS. 

{Ilio-trochanterius  Magnus.) 

(Pl.  III.  30  ;  Fig.  84,  c.) 

This  is  a  very  large  muscle  occupying  the  iliac  dorsum,  and 
stretching  forwards  over  the  lumbar  region  ;  it  is  fleshy  and  thick 
in  its  centre,  terminating  in  t"ft^o  tendons. 

Origin. — From  the  iliac  shaft,  crest,  dorsum,  and  spines, 
anterior  and  posterior,  the  side  of  the  sacrum,  the  sacral  and  part 
of  the  sacro-sciatic  ligaments,  and  the  tendinous  envelope  of  the 
longissimus  dorsi  as  far  forward  as  the  last  rib. 

Insertion. — By  two  tendons,  one  to  the  summit  of  the  tro- 
chanter major,  the  other  anteriorly  to  the  crest  below  the  con- 


GLUTEAL    REGIOJN-.  233 

Yexity,  over  which  it  passes,  with  an  interposed  synovial  bursa  ;  a 
small  fleshy  insertion  is  often  found  posteriorly. 

Relation. — Externally  with  the  extemus  and  the  fascia; 
internally  with  the  internus,  sacro-sciatio  ligament,  and  the 
ilium  ;  anteriorly  with  the  fascia  lata  and  the  longissimus  dorsi ; 
posteriorly  with  the  triceps  abductor  femoris.  The  inner  and 
anterior  portion  which  terminates  in  the  anterior  tendon  has 
been  rather  unnecessarily  described  as  a  separate  muscle;  this 
possible  separation  is  shown  in  Fig.  83.  a. 

Action. — To  extend  the  femur  on  the  pelvis,  and  when  the 
posterior  limbs  are  fixed,  to  assist  in  rearing. 


Deep-seated  muscles  of  the  gluteal  region,  a,  Deep  anterior  portion  of 
gluteus  maximus  ;  6,  Gluteus  internus  ;  c.  Common  tendon  of  obturator 
inlemus  and  pyriformis ;  d  d,  Gemellus  anticus  and  posticus ;  e,  Ischio- 
femoralis. 


GLUTEUS   INTERNUS. 

{Ilio-trochanterms  Parvus.) 

(Fig.  83.  6.) 

Situated  underneath  the  maximus  and  above  the  hip  joint, 
this  is  a  short  and  fan-shaped  muscle,  the  fibres  converging 
outwards. 

OHgin. — From  the  shaft  of  the  ilium,  the  ischiatic  spine,  and 
the  capsular  ligament  of  the  hip  joint. 


234  MYOLOGY. 

InseHion. — By  a  tendon  to  a  roughened  space  inside  the  con- 
vexity of  the  trochanter  major  of  the  femur. 

Relation. — Externally  with  the  maximus  ;  internally  with  the 
femur  and  hip  joint. 

Action. — ^To  abduct  the  thigh,  and  rotate  it  inwards. 


RECTUS   PARVUS. 
(Ilio-femoralis  Parvus — Grele.) 

Situated  in  front  of  the  hip  joint,  this  is  a  very  small,  pale^ 
and  fusiform  muscle,  with  a  fleshy  belly,  and  tendinous  ex- 
tremities. 

Origin. — From  the  brim  of  the  acetabulum,  towards  the  out- 
side ;  or  it  may  be  by  two  origins,  an  outer  one,  and  one  from 
between  the  tendons  of  origin  of  the  rectus  femoris,  and  the 
capsular  ligament  of  the  hip  joint. 

Insertion. — To  the  anterior  and  upper  part  of  the  femur,  just 
below  the  hip  joint,  by  aponeurotic  slips. 

Relation. — Externally  and  internally  with  the  rectus  femoris ; 
posteriorly  with  the  capsular  ligament. 

Action.-^liO  tense  the  capsular  ligament  of  the  hip  joint 
during  flexion  of  the  femur. 


OBTURATOR    EXTERNUS. 
{Suhpuhio-troclianterius-  Externus.) 

Placed  on  the  inferior  surface  of  the  os.  innominatum,  below 
the  obturator  foramen,  which  it  covers,  this  muscle  is  flat,  thick, 
and  triangular,  its  belly  consisting  of  delicate  fasciculi,  which  pass 
outwards. 

Origin. — From  the  surface  of  the  pubis  and  ischium,  attached 
to  the  obturator  ligament. 

Insertion. — In  the  trochanteric  fossa. 

Relation. — Inferiorly  with  the  pectineus  and  adductors  ;  supe- 
riorly with  the  capsular  ligament  of  the  hip  joint  and  obturator 
ligament ;  posteriorly  with  the  triceps  abductor  and  iscl»*'o- 
femoralis. 

Action. — To  rotate  the  femur  outwards,  and  adduct  it. 


GLUTEAL   REGION.  235 

OBTURATOR   INTERNUS. 

{Suhpubio-troclianteriits  Internus.) 

(Fig.  83.  c.) 

Situated  ou  the  floor  of  the  pelvic  cavity,  covering  the  obturator 
foramen,  and  corresponding  to  the  extemus;  it  is  fan-shaped, 
with  a  delicate,  fleshy  belly,  terminating  in  a  flat  tendon. 

Origin. — From  the  border  of  the  obturator  foramen  and  its 
ligament ;  it  passes  through  the  lesser  sciatic  notch,  behind  the 
acetabulum,  where  its  tendon  joins  that  of  the  pyriformis. 

Insertion. — In  the  trochanteric  fossa. 

Relation. — Superiorly  with  the  pelvic  fascia ;  inferiorly  with 
the  obturator  ligament,  ischium,  and  pubis ;  outside  the  pelvis, 
with  the  sciatic  nerve  above,  and  the  externus  below. 

Action. — To  rotate  the  femur  outwards,  and  perhaps  to  abduct 
it  slightly. 

PYRIFORMIS. 

(Sacro-trochanterius. ) 

(Fig.  83.  c.) 

Situated  laterally  in  the  pelvic  cavity,  this  is  a  flat,  elongated, 
semipenniform  muscle,  with  a  small  tendon  of  insertion. 

Origin. — From  the  transverse  processes  of  the  sacral  vertebrae, 
and  the  inner  surface  of  the  iliac  shaft ;  lying  along  the  inner 
side  of  the  sacro- sciatic  ligament,  it  passes  through  the  lesser 
sciatic  notch  to  join  the  tendon  of  the  obturator  internus. 

Insertion. — In  the  trochanteric  fossa. 

Relation. — With  the  pelvic  •  fascia  internally ;  externally  with 
the  OS  innominatum ;  outside  the  pelvis  it  is  crossed  by  the 
sciatic  nerves  ;  the  obturator  vessels  and  nerves  pass  along  its 
lower  border. 

Action. — To  rotate  the  femur  outwards. 

GEMELLUS   ANTICUS   AND   POSTICUS. 

(Gemini — Ischio-trochanterii.) 

(Fig.  83.  d  d.) 

A  pair  of  very  delicate  muscles,  variable  in  form,  and  usually 
situated  one  above  and  before,  the  other  below  and  behind  the 
obturator  internus  tendon,  with  fleshy  bellies  and  tendinous 
insertions. 


236  MYOLOGY. 

Origin. — From  the  shaft  of  the  ischium  ou  either  side  of  the 
conjoined  tendon  of  the  pyriformis  and  obturator  internus,  their 
fibres  blending  with  it  and  passing  outwards.  There  may  be 
another  flat  and  somewhat  large  muscle  sitftated  between  the 
above  and  the  obturator  externus,  originating  also  from  the 
ischial  ramus. 

Insertion. — In  the  trochanteric  fossa. 

Relation. — Posteriorly  with  the  sciatic  nerves ;  anteriorly 
with  the  capsular  ligament  of  the  hip  joint,  and  the  obturator 
externus. 

Action. — Like  the  preceding,  to  rotate  the  femur  outwards. 

Femoral  Region. 

The  muscles  of  this  regiou  cover  more  or  less  the  shaft  of  the 
femur,  some  of  them  reaching  as  far  as,  or  below  the  stifle  joint ; 
the  majority  of  them  have  a  pelvic  origin.-  These  muscles  may 
be  conveniently  divided  into  the  four  following  groups  : — 

Internal.  I  Anterior. 

External.  I  Posterior. 


Internal  Femoral  Group. 

adductors. 

These  form  the  large  fleshy  mass  situated  between  the  inferior 
pelvic  surface  and  the  stifle  joint ;  they  are  six  in  number  : — 

Sartorius. 

Gracilis. 

Pectiueus. 

Adductor  brevis.    ^ 

Adductor  longus.     r  Triceps  adductor  feraoris. 

Adductor  maguus.  J 

SARTORIUS. 

(Sublujnbo-tibialis.) 
(Fig.  77.  I.) 

Situated  in  the  abdominal  cavity  at  the  pelvic  inlet,  and  along 
the  inner  aspect  of  the  thigh,  it  is  long,  thin,  fleshy,  and  pyra- 
midal, extending  obliquely  downwards,  forwards,  and  outwards. 


INTERNAL    FEMORAL    GROUP.  237 

Origin. — From  the  brim  of  the  pelvis,  and  from  the  iliac 
fascia,  near  the  tendon  of  the  psoas  pan^us. 

Insertion. — lu  common  with  the  gracilis,  by  fascia  to  the 
internal  straight  ligament  of  the  patella. 

Relation. — Anteriorly  with  the  crural  arch  and  fascia ;  inter- 
nally with  the  psoas  magnus  and  iliacus;  posteriorly  with  the 
gracilis,  pectiueus,  and  vastus  intemus.  Its  posterior  border  is 
related  with  the  femoral  artery,  which,  with  the  vein  and  internal 
saphenic  nerre,  passes  through  a  space  included  between  this 
muscle,  the  iliacus,  and  the  pectineus,  termed  the  femoral  space. 

Action. — To  adduct  and  flex  the  femur. 


GRACILIS. 

(Sicbpubio-tiblalis.) 
(Fici.  77,  c.) 

Situated  on  the  internal  part  of  the  thigh,  this  is  a  broad, 
thin,  quadrilateral  muscle,  directed  downwards  and  outwards.  It 
has  a  flat  fleshy  belly,  terminating  in  a  broad  aponeurosis. 

OrifjirL — From  the  inferior  surface  of  the  ischio-pubic  sym- 
physis, where  it  meets  its  fellow. 

InseHion. — With  the  sartorius,  to  the  internal  straight  liga- 
ment of  the  patella,  and  also  to  the  supero-internal  part  of  the 
tibia ;  posteriorly  its  fascia  blends  with  that  of  the  biceps  rotator 
tibialis,  the  two  forming  the  fascia  of  the  region. 

Relation. — Anteriorly  with  the  sartorius;  internally  with  the 
adductor  muscles  of  the  thigh  ;  posteriorly  with  the  biceps  rotator 
tibialis  ;  externally  with  the  crural  aponeurosis  and  saphenic 
vein. 

Actiom. — To  adduct  the  limb,  and  tense  the  fascia  of  the  les. 


PECTINEUS. 

{Super-puhio-femoralis. ) 

(Fia.  76./.) 

Situated  on  the  inner  side  of  the  preceding,  this  muscle  is 
conical,  the'  fibres  extending  outwards  and  backwards.  It  is 
tendinous,  with  a  fleshy  belly,  bifid  superiorly  for  the  passage  of 
the  pubio-femoral  ligament. 


238  MYOLOGY. 

Origin. — From  the  brim  and  inferior  surface  of  the  pubis  ;  it 
is  also  attached  to  the  pubio-femoral  ligament,  which  passes 
through  its  tendons  of  origin. 

Insertion. — To  a  roughened  surface'  on  the  inner  side  of  the 
femur,  below  the  internal  trochanter,  and  near  the  nutrient  fora- 
men. 

Relation. — Anteriorly  with  the  sartorius,  part  of  the  psoas 
magnus,  iliacus,  and  vastus  internus ;  posteriorly  with  the  adductor 
brevis  and  gracilis  ;  superiorly  with  the  obturator  extemus.  The 
femoral  vessels  cross  it. 

Action. — To  adduct  and  flex  the  thigh,  and  to  rotate  it  in- 
wards. 


TRICEPS   ADDUCTOR   FEMORIS. 

This  name  has  been  applied  to  a  group  of  three  muscles,  situ- 
ated on  the  inner  surface  of  the  thigh,  and  covered  by  the  gracilis, 
which  act  the  part  of  adductors.  They  have  also  been  described 
as  consisting  of  a  biceps  and  a  single  muscle ;  we  describe  them 
as  three  distinct  muscles,  and  name  them,  from  before  backwards, 
the  brevis,  the  longus,  and  the  magnus. 


ADDUCTOR   BREVIS. 

(Subpubio-jemoralis.) 

(Fig.  76.  g.) 

Situated  on  the  .inner  aspect  of  the  thigh,  behind  the  pec- 
tineus,  this  muscle  is  pyramidal,  with  the  base  upwards,  its  fibres 
converging  downwards  and  outwards.  Fleshy,  with  tendinous 
insertions  inferiorly,  it  is  often  somewhat  blended  with  the 
longus. 

Origin. — Superiorly  from  the  inferior  surface  of  the  pubis. 

Insertion. — To  a  square,  roughened  surface  on  the  posterior 
part  of  the  shaft  of  the  femur,  about  the  middle,  together  with  a 
portion  of  the  long  adductor. 

Relation. — Anteriorly  with  the  pectineus  ;  posteriorly^  with  the 
longus ;  externally  with  the  gracilis  ;  internally  with  the  obturator 
extemus.  • 

Action. — To  flex,  adduct,  and  rotate  the  femur  outwards. 


EXTEBNAL    FEMORAL    REGION.  239 

ADDUCTOR    LONGDS. 
[Subpuhio-femoralis  Posterior.) 
(Fig.  76.  h.) 

Situated  on  the  inner  aspect  of  the  thigh,  covered  by  the 
-gracilis,  this  muscle  is  long,  flat,  and  prismatic,  extending  outwards 
and  downwards. 

Origin. — From  the  inferior  surface  of  the  posterior  part  of  the 
pubis. 

Insertion. — By  two  divisions,  one  attached  by  the  insertion  of 
the  brevis,  the  other,  with  the  magnus,  above  the  internal  condyle 
of  the  femur  at  the  attachment  of  the  lateral  ligament. 

Relation. — Anteriorly  with  the  brevis  and  obturator  externus  ; 
posteriorly  with  the  magnus  ;  externally  with  the  gracilis  ;  inter- 
nally with  the  ischio-femoralis  and  sciatic  nerves.  The  femoral 
vessels  pass  between  its  two  divisions. 

Action. — To  adduct  the  femur,  and  rotate  it  outwards. 

ADDUCTOR    MAGNUS. 

{Semimembranosus — Ischio-tibialis.) 

(Fig.  76.  i.) 

Placed  behind  the  preceding,  on  the  postero-internal  part  of  the 
thigh,  this  muscle  is  thin  at  its  extremities  and  posterior  border, 
thick  and  fleshy  elsewhere,  terminating  in  a  short  tendon. 

Origin. — Chiefly  from  the  inferior  surface  and  tuberosity  of 
the  ischium  by  tendinous  fibres,  and  by  a  slender  band  from  the 
coccygeal  fascia. 

Insertion. — To  a  small  roughened  surface  on  the  inner  side 
of  the  internal  condyle  of  the  femur 

Relation. — Anteriorly  with  the  longus,  to  which  it  is  very 
adherent ;  externally  wi  ua  the  gracilis ;  posteriorly  with  the  biceps 
rotator  tibialis  ;  internally  with  the  triceps  abductor. 

Action. — To  adduct  and  extend  the  thigh.  If  the  limb  be 
iixed,  it  assists  in  raising  the  anterior  parts  of  the  trunk  in 
^'rearing." 

External  Femoral  Region. 

abductors. 

This  region  contains  only  one  muscle,  which  is  situated  laterally 
with  respect  to  the  haunch,  but  more  posteriorly  with  regard  to 
the  femur. 


240 


MYOLOGY. 


TRICEPS    ABDUCTOR    FEMORIS. 

{Ischio-tibialis  Fxtermis.) 

(Pl.  II.  55;  Fig.  84.  d  d  d.) 

Situated  on  the  external  part  of  the  haunch,  behind  and  below 
the  great  gluteal  muscles,  this  is  a  very  large  and  fleshy  muscle. 


Via.  84. 

Muscles  0*  the  thigh  and  haunch— left  side ;  the  external  fascia  being  removed, 
o,  Tensor  fasciae  latse ;  6,  Gluteus  externus ;  c,  Gluteus  maximus  ',  d  d  d.  Triceps 
abductor  femorls  ;  e  e.  Biceps  rotator  tibialis  ;  /,  Part  of  adductor  magnus. 


made  up  of  two  prismatic  portions,  with  two  origins  and  three 
insertions.  The  anterior  portion  is  much  the  longer.  The  fibres 
pass  downwards  in  a  somewhat  curved  manner,  the  larger  con- 
vexity being  to  the  rear. 


ANTERIOR    FEMORAL    REGION.  241 

Origin. — The  anterior  portion  arises  from  the  spine  of  the 
sacrum,  the  coccygeal  fascia,  and  the  sacro-sciatic  ligament ;  also 
from  the  ischial  tuberosity  ;  the  posterior  portion  is  attached  to 
the  crest  of  the  ischial  tuberosity. 

Insertion. — Anteriorly  to  the  external  side  of  the  patella  and 
its  external  ligament,  a  synovial  bursa  lying  between  it  and  the 
bone  ;  posteriorly  by  a  strong  aponeurosis  to  the  tibial  fascia, 
which  it  helps  to  form,  and  by  it  to  the  tibial  crest.  It  sends  a 
strong  slip  which  is  attached  near  the  insertion  of  the  ischio- 
femoralis. 

Relation. — Externally  and  superiorly  with  the  gluteal  fascia^ 
to  which  it  adheres  above ;  internally  with  the  fascia  of  the 
gluteus  externus,  which  separates  it  from  the  maximus  and  th6 
femoral  trochanter  ;  with  the  sciatic  nerves,  the  adductor  muscles^ 
and  biceps  rotator,  excepting  at  the  upper  portion,  where  it  is. 
related  posteriorly  with  the  latter  muscle. 

Action. — The  anterior  portion  extends  the  femur  and  abducts, 
the  limb  ;  the  posterior  portion  flexes  the  stifle  joint  and  tenses 
the  tibial  fascia.  It  assists  the  abductor  magnus  when  the  limb 
is  fixed.      (Vide  Abductor  Magnus.) 


Anterior  Femoral  Region. 

The  muscles  of  this  region  lie  in  the  space  between  the  iliac 
spine  above,  the  patella  below,  and  the  femur  and  hip  joint 
posteriorly.      They  are  as  follows  : — 

Tensor  fasciae  latse. 

Rectus  femoris.        \ 

Vastus  externus.     f  _,  .  ,  .  ,. 

tT    .      •  .  r  Tnceps  or  quadriceps  cruralis. 

V  astus  intemus.     i 

Crureus.  ^ 


TENSOR   FASCL^   LAT^. 

{Tensor   Vagince  Femoris — Ilio-aponeuroticus.) 
(Pl.  n.  54 ;  Fig.  84.  a.) 

.  Situated  in  front  of  the  gluteus  externus,  and  on  the  outside 
of  the  vastus  externus,  this  muscle  is  flat  and  triangular,  radiat- 
ing downwards  and  backwards. 

Attachments. — The  fleshy  portion  arises  from  the  anterior  iliac 


242  MYOLOGr. 

spine,  and  from  It  springs  the  aponeurotic  expansion  termed  the 
fascia  lata.     (See  Fasciae  of  the  Posterior  Limb,  p.  255.) 

Relation. — Internally  with  the  iliacua,  rectus  femoris,  and 
vastus  .externus  ;  externally  with  the  skin  ;  posteriorly  with  the 
gluteus  maximus  and  externus;  anteriorly  with  the  precrural 
lymphatic  glands. 

Action. — It  assists  in  flexing  the  femur,  raising  the  limb  ;  and 
it  tenses  the  fascia  lata. 


.     CRURAL   MUSCLES. 

The  remaining  muscles  of  this  region,  being  all  of  them 
inserted  to  the  patella,  may  be  described  as  a  single  muscle,  the 
triceps  or  quadriceps  cruralis ;  or  the  rectus  may  be  regarded 
as  a  single  muscle,  and  the  other  three  described  together  as  the 
triceps  cruralis ;  or,  again,  they  may  be  considered  as  separate 
muscles.  The  above  names  being  borne  in  mind,  the  last  is 
perhaps  the  simplest  method,  and  is  the  one  adopted  here. 
These  muscles  are  considerably  blended,  and  cannot  well  be 
perfectly  separated  without  cutting  muscular  fibre. 


RECTUS    FEMORIS. 

{Ilio-rotvlejis.) 

(Pl.  IIL  34j  Fig.  76.  Z.) 

Situated  on  the  anterior  part  of  the  thigh,  between  the  two 
vasti,  it  is  thick,  elongated,  and  fusiform,  consisting  of  two  short, 
flat  tendons  of  origin,  and  a  fleshy  intersected  belly,  terminating 
in  a  conical  aponeurotic  envelope.  It  is  directed  downwards  and 
forwards. 

Origin. — From  two  depressions,  one  on  each  side  of  the  iliac 
shaft,  just  before  the  acetabulum. 

Insertion. — To  the  upper  part  of  the  patella. 

Relation. — It  lies  between  the  vasti,  and  above  the  crureus, 
and  superiorly  between  the  iliacus  and  the  tensor  fasciae  latse, 
with  which  it  is  related  anteriorly.  A  pad  of  fat  occupies  the 
space  between  its  tendons  of  origin  and  the  capsular  ligament  of 
the  hip  joint. 

Action. — To  flex  the  femur,  and  extend  the  leg. 


ANTERIOR   FEMOEAL    REGION.  24$ 

VASTUS  EXTERNUS. 
{Femoro-rotuleus  Exterwus.) 
(PL.  III.  35.) 
Situated  on  the  outer  side  of  the  rectus  femoris,  this  muscle 
is  broad,    thick,  flattened  laterally,   and    semi-ovoid,    extending 
downwards  and  forward^s;    it   is   fleshy,   with    strong  tendinous 
intersections. 

Origin. — From  the  external  and  part  of  the  anterior  aspects 
of  the  shaft  of  the  femur,  and  from  the  base  of  the  trochanter 
major  downwards. 

Insertion. — To  the  upper  and  outer  part  of  the  patella;  or 
it  may  join  the  rectus  femoris. 

Relation. — Externally  with  the  tensor  fasciae  latse,  and  gluteus 
I'xternus  ;  internally  with  the  rectus,  crureus,  and  vastus  intemus,. 
with  which  inferiorly  it  is  intimately  blended  ;  posteriorly  with 
the  triceps  abductor  femoris  and  the  femur. 
Action. — To  extend  the  leg. 

VASTUS  INTERNUS. 

(Femoro-rotuleus  Intemus.) 

(Fig.  76.  k.) 

Corresponding  to  the  externus,  this  muscle  is  situated  on  the 
inner  side  of  the  rectus  femoris,  the  two  forming  a  channel  in 
which  are  lodged  the  rectus  and  crureus.  It  is  semi-ovoid,  and 
fleshy,  becoming  tendinous  at  its  insertion. 

Origin. — From  the  neck  of  the  femur,  its  antero-internal 
surface,  and  the  trochanter  internus. 

Insertion. — To  the  upper  and  inner  side  of  the  patella. 

Relation. — Externally  with  the  rectus ;  internally  with  the 
sartorius,  pectineus,  psoas  magnus,  iliacus,  adductor  magnus,  and 
crural  fascia. 

Action. — To  extend  the  leg. 

CRUREUS. 

(Femoro-rotuleus  Medius.) 

Situated  below  the  rectus,  and  between  the  two  vasti,  this 
muscle  is  small,  cylindrical,  fleshy,  and  tendinous  at  its  extremi- 
ties ;  it  is  separated  from  the  vasti  with  difficulty. 


.244  MYOLOGY. 

Origin. — From  about  the  lower  third  of  the  anterior  surface 
of  the  femur. 

Insertion. — To  the  upper  surface  of  the  patella,  and  the 
capsular  ligament  of  the  joint. 

Relation. — Anteriorly  with  the  rectus;  posteriorly  with  the 
femur  ;  laterally  with  the  vasti. 

Action. — To  assist  the  vasti,  and  tense  the  capsular  ligament. 

Posterior  Femoral  Region. 
This  region  contains  two  muscles,  a  large  superficial  one,  and 
a  small  one  deeply  situated ;  they  are  as  follows  : — 
Biceps  rotator  tibialis. 
Iscbio-fem  oralis. 

BICEPS  ROTATOR  TIBIALIS. 

{Semitendinosus — Ischio-tibialis  Posticus. ) 

(Pl.  II.  61  ;    Fig.  84.  e.  e.) 

Situated  behind  the  triceps  abductor,  and  curved  like  it,  with 
the  convexity  behind,  this  muscle  is  long,  cylindrical,  and  bifid 
above,  consisting  of  pale,  fleshy  fibres,  divided  by  a  strong 
aponeurosis. 

Origin. — By  one  head,  from  the  spine  of  the  sacrum,  and 
the  sacro-sciatic  ligament,  in  common  with  the  triceps  abductor; 
the  other,  which  is  considerably  shorter,  comes  from  the  ischial 
.tuberosity. 

Insertion. — To  the  supero-internal  part  and  anterior  crest  of 
the  tibia,  its  aponeurosis  blending  with  the  tibial  fascia  and 
the  periosteum. 

Relation. — Superiorly  and  posteriorly  it  is  covered  by  the 
gluteal '  fascia,  and  its  sacral  portion  partly  covers  the  triceps 
abductor,  being  related  with  it  and  the  sciatic  nerves  anteriorly ; 
externally  with  the  abductor  magnus. 

Action. — To  extend  the  femur,  flex  and  rotate  the  leg  out- 
swards,  and  tense  the  tibial  fascia. 

ISCHIO-FEMORALIS. 

{Quadraius  Femoris.) 

(Fig.  83.  e.) 

Situated  behind  the  femur,  between  the  adductor  and  abductor 
muscles.  This  muscle  consists  of  a  flattened  band,  running  down- 
awards  and  outwards. 


ANTERIOR   TIBIAL    GROUP.  245 

Origin. — From  the  inferior  surface  of  the  ischium,  in  front  of 
the  tuberosity. 

Insertion. — To  a  linear  imprint  on  the  posterior  surface  of  the 
femur,  just  below  the  level  of  the  trochanter  intemus. 

Relation. — Anteriorly  with  the  femur  and  obturator  externus  ; 
posteriorly  and  externally  with  the  adductor  magnus ;  internally 
with  the  gemellus  posticus,  and  the  sciatic  nerves. 

Action. — To  extend  and  adduct  the  femur,  but  not,  in  the 
horse,  to  rotate  it. 

Tibial  Region. 

This  region  corresponds  to  the  antibrachial  region  of  the 
anterior  limb,  and,  like  the  latter,  contains  chiefly  flexor  and 
extensor  muscles.  The  strong  tibial  fascia  invests  the  region, 
and  is  attached  to  the  tibial  crest,  and  to  the  summit  of  the 
calcaneum,  being  tensed  by  the  gracilis  and  other  muscles. 
The  muscles  of  this  region  cover  the  tibia  and  fibula,  except  on 
the  inner  side  of  the  former,  and  they  consist  of  an  anterior  and 
a  posterior  group ;  but  as  the  flexor  side  of  the  tarsal  joint  is 
anterior,  and,  in  the  joints  below,  posterior,  we  find  flexor  and 
extensor  muscles  both  before  and  behind.  In  the  anterior  limb 
it  is  not  so,  the  carpus  and  the  joints  beloAV  all  flexing  in  the 
same  direction. 

Anterior  Tibial  Group. 

We  subdivide  this  group  into  the  flexors  and  extensors;  there 
are  two  of  the  latter  and  only  one  of  the  former. 

Flexor.  Extensors. 

Flexor  metatarsi.  I  Extensor  pedis. 

I  Peroneus. 

FLEXOR   METATARSL 

(Tibio-premetatarseus.) 

(Fig.  85.  a.) 

This  muscle  is  situated  on  the  antero-external  aspect  of  the  leg, 
and  consists  of  two  distinct  parts,  one  fleshy,  the  other  tendinous. 
The  tendinous  portion  appears  as  a  very  strong  fibrous  cord,  situ- 
ated in  front  of  the  fleshy  portion,  and  running  the  whole  length 
of  the  muscle.  The  fleshy  portion  is  coniform,  thick  above,  and 
thinner  below. 


246 


MYOLOGY. 


Fig.  85. 

Anterior  tibial  group  of  muscles  of  the 
right  limb,  seen  from  before  and  the  out- 
side, a.  Flexor  metatarsi ;  a',  Tendon  to 
the  cuboid ;  and  a".  Tendon  to  the  meta- 
tarsus, from  its  funicular  portion ;  a'". 
Tendon  of  its  fleshy  portion,  sending  a 
straight  slip  to  the  metatarsus,  and  an 
oblique  one  to  the  cuneiform  bone ;  b.  Ex- 
tensor pedis ;  V,  Its  tendon;  c,  Peroneus: 
c',  Point  where  its  tendon  joins  that  of 
the  extensor  pedis ;  d.  Extensor  pedis 
brevis ;  e,  Superior,  and  /,  Inferior  thick 
portions  of  the  annular  ligament. 


Attachments. —T  The  tendinous- 
portion  arises  from  the  depression 
between  the  trochlea  and  condyle  of 
the  femur,  and  lies  in  the  superior 
tibial  groove,  clothed  above  by  a 
reflection  of  one  of  the  synovial 
membranes  of  the  stifle  joint ;  below 
this  point  it  gives  attachment  to 
fibres  of  the  fleshy  portion  and  of 
the  extensor  pedis  ;  in  front  of  the 
astragalus  it  forms  a  ring,  through 
which  the  tendon  of  the  fleshy  por- 
tion passes ;  at  the  tarsus  it  bifur- 
cates, a  very  strong  slip  being  at- 
tached to  the  large  metatarsal  bone, 
and  a  small  one,  which  inclines  out- 
wards, to  the  cuboid  bone. 

The  fleshy  portion  arises  from- 
the  head  of  the  tibia,  and  its  groove, 
also  from  the  tendinous  part,  receiv- 
ing slips  from  the  latter;  its  tendon 
of  insertion,  after  passing  through, 
the  above-named  ring,  bifurcates, 
and  is  inserted  by  a  broad  portion 
to  the  front  of  the  great  metatarsal 
bone,  and  by  a  smaller  slip,  which 
winds  inwards,  to  the  small  cunei- 
form bone. 

Relation. — Anteriorly  with  the 
extensor  pedis;  posteriorly  with  the 
external  aspect  of  the  tibia,  and  the 
anterior  tibial  artery. 

Action. — It  flexesthe  tarsal  joint. 
The  tendinous  portion  may  be  re- 
garded as  a  strong  fibrous  com- 
munication between  the  femur  and 
the  metatarsus,  which,  when  the 
stifle  joint  is  flexed,  becomes  tensed, 
and  mechanically  repeats  the  action, 
upon  the  joint  below. 


ANTERIOR    TIBIAL    GROUP.  247 

EXTENSOR    PEDIS. 

{Femoro-pi'ephalcmgeus.) 

(Fig.  85.  I.) 

Situated  on  the  anterior  surface  of  tlae  tibia  and  bones  below 
this  is  a  long^  fusiform  muscle,  extending  downwards  and  back- 
wards. A  little  above  the  tarsus,  the  belly  terminates  in  a  long, 
flat  tendon,  which,  bound  down  by  the  three  bands  of  the  annular 
ligament,  passes  down  the  front  of  the  tarsus  and  metatarsus, 
near  the  middle  of  which  it  receives  the  extensor  brevis  and  the 
tendon  of  the  peroneus  ;  the  united  tendon  now  passes  down,  and 
is  arranged  like  that  of  the  anterior  limb. 

Origin. — From  the  fossa  between  the  trochlea  and  external 
condyle  of  the  femur,  by  the  tendon  of  the  flexor  metatarsi, 
common  to  it. 

Insertion. — To  the  capsular  ligament  of  the  fetlock  joint,  the 
anterior  surface  of  the  two  first  phalanges,  and  the  pyramidal 
process  of  the  os  pedis. 

Relation. — Anteriorly  with  the  fascia;  internally  with  the 
flexor  metatarsi ;  posteriorly  with  the  peroneus. 

Action. — To  extend  the  entire  digit,  and  flex  the  tarsal  joint. 


p-ERONEUS. 

{Peroneo-prephalangeus. ) 

(Fig.  85.  c.) 

Situated  on  the  external  side  of  the  leg,  this  is  a  long  and 
somewhat  penniform  muscle,  consisting  of  a  prismatic,  fleshy  belly, 
which  originates  by  a  short,  and  terminates  by  a  long  tendon  ; 
the  latter  passes  through  a  theca  on  the  external  side  of  the 
tarsus,  joining  the  tendon  of  the  extensor  pedis  below  the  joint. 

Origin. — From  the  external  lateral  ligament  of  the  stifle  joint, 
and  the  entire  length  of  the  fibula. 

Insertion. — It  joins  the  tendon  of  the  extensor  pedis. 

Relation. — Externally  with  the  fascia;  anteriorly  with  the 
extensor  pedis  ;  posteriorly  with  the  flexor  pedis  perforans. 

Action. — It  assists  the  extensor  pedis. 


248 


MYOLOGY. 


Posterior  Tibial  Group. 


For  convenience  of  description,  we  subdivide  the  muscles  of  this 
group,  but  the  subdivision  is  a  somewhat  artiJ&cial  one,  as  some 
of  the  muscles  have  two  actions,  flexing  one  joint  and  extending 
another. 

Extensors. 


Gastrocnemius. 
Plantaris. 

Flexors. 

Flexor  pedis  perforatus. 
Plexor  pedis  perforans. 
Flexor  pedis  accessorius. 
Popliteus. 


GASTROCNEMIUS. 

(Bifevi  ero-crjcaneus, ) 
(PL.  III.  38.) 

Situated  at  the  back  of  the  leg,  this  muscle  is  somewhat  heart- 
shaped,  ending  in  a  flattened  tendon  ;  the  fleshy  belly  is  divisible 
into  two  portions,  and  intersected  superiorly  by  strong  tendons. 

Origin. — By  two  heads ;  one  from  a  ridge  extending  upwards 
from  the  external  condyle  in  front  of  the  supracondyloid  fossa ; 
the  other  from  the  posterior  surface  of  the  femur,  just  above  the 
intercondyloid  fossa,  and  from  the  internal  condyle. 

Insertion.  —  To  the  posterior  part  of  the  summit  of  the 
calcaneum,  a  synovial  bursa  being  interposed  between  it  and  the 
anterior  part,  over  which  it  passes. 

Relation. — Anteriorly  with  the  flexor  perforatus,  popliteus, 
popliteal  vessels  and  nerves,  and  the  vastus  externus  above ; 
posteriorly  with  the  triceps  abductor  femoris ;  internally  with 
biceps  rotator  tibialis ;  superficially  with  the  tibial  fascia ; 
inferiorly  the  tendon  is  covered  by  that  of  the  flsxor  perforatus, 
the  two  forming  the  Tendo-AcMllis. 

Action. — To  extend  the  tarsal  joint. 


POSTERIOE   TIBIAL  GROUP.  249 

PLANTARIS. 

{Soleus — Peroneo-calcaneus.) 
(Pii.  III.  39.) 

Situated  on  the  postero-external  part  of  the  leg,  to  the  out- 
side of  the  gastrocnemius,  this  muscle  is,  in  the  horse,  slender 
find  rudimentary,  with  a  small,  delicate  tendon  of  insertion. 

Origin. — From  the  external  part  of  the  head  of  the  fibula. 

Insertion. — Together  with  the  tendon  of  the  gastrocnemius  to 
the  point  of  the  calcaneum. 

Relation. — Externally  with  the  fascia ;  internally  with  the 
gastrocnemius. 

Action. — It  assists  very  slightly  the  gastrocnemius. 


FLEXOR    PEDIS    PEKFORATUS.* 

{Femoro-phalangeus. ) 

(Fig.  86  6.) 

Situated  immediately  underneath  the  gastrocnemius,  this 
muscle  is  in  shape  funicular,  consisting  of  a  strong  fibrous  cord, 
with  a  slightly  fleshy  portion  above,  and  arising  from  the  supra- 
<3ondyloid  fossa ;  the  belly  is  succeeded  by  a  strong  tendon, 
united  to  fascia,  which  is  fixed  to  the  inner  surface  and  ridge  of 
the  tibia  and  the  summit  of  the  calcaneum,  being  continuous 
with  the  tibial  fascia,  and  enclosing  the  entire  tendo-Achillis. 
The  tendon,  at  first  under  that  of  the  gastrocnemius,  winds 
round  its  inner  side,  and  then  surmounts  it;. on  reaching  the 
point  of  the  calcaneum  it  forms  a  cap,  giving  slips  of  insertion  to 
the  sides  of  that  bone  ;  a  large  synovial  bursa  exists  here,  which 
is  one  of  the  seats  of  the  lesion  termed  capped  hock.  It  now 
descends  posteriorly,  and  is  disposed  as  is  the  corresponding 
tendon  in  the  anterior  extremity,  forming  a  synovial  sheath  and 
ring  for  the  perforans  tendon,  and  finally  bifurcating  to  become 
attached  to  the  sides  of  the  os  coronse. 

Relation. — Posteriorly  with  the  gastrocnemius ;  anteriorly 
with  the  tibia,  the  popliteus,  perforans,  and  accessorius  muscles. 

*  This  muscle  was  formerly  described  under  the  name  of  gastrocnemius 
intemus.     The  more  appropriate  one  now  in  use  is  adopted  here. 


250 


MYOLOGY. 


Action. — To  flex  the  fetlock  and  pastern  joints,  and  assist  iit 
extending  the  tarsus  ;  when  the  animal 
is  stationary,  it  serves  mechanically,  a* 
a  fibrous  band,  to  prevent  flexion  of 
the  tarsal  joint. 


FLEXOR   Pm)IS   PERFOBANS. 

(  Tibio-phalangeua. ) 

(Fig.  86.  c.) 

Situated  on  the  posterior  aspect  of 
the  leg,  extending  from  the  head  of 
the  tibia  to  the  distal  phalanx,  this 
muscle  is  thick  and  prismatic,  consist- 
ing of  a  fleshy,  intersected  belly  and 
long  tendon  of  insertion.  The  belly  is 
partially  bifid,  the  internal  portion 
being  the  larger.  The  tendon  com- 
mences a  little  above  the  hock,  passes 
through  the  groove  on  the  inner  side 
of  the  calcaneum,  first  crossing  the 
posterior  capsular  ligament  of  the 
tarsus,  where  it  is  bound  down  by 
fibrous  tissue,  in  a  synovial  sheath,  the 
usual  seat  of  Thorough-pin.  It  then 
descends  behind  the  metatarsal  bone  ; 
about  half-way  down,  it  is  joined  by 
the  check  ligament,  which  springs  from 
the  lower  bones  of  the  tarsus  and  head 
of  the  metatarsal  bone,  and  is  similar 
to,  but  considerably  less  than,  that  of 
the  fore  extremity.  It  is  joined  above 
by  the  tendon  of  the  flexor  accessorius, 
and  is  otherwise  disposed  exactly  as 
the  perforans  tendon  of  the  anterior 
extremity. 

Origin. — From  the  roughened  pos- 
terior aspect,  and  head  of  the  tibia,  the 
fibula,  and  fibulo-tibial  ligament. 

Insertion. — To  the  semilunar  ridge 
on  the  solar  surface  of  the  os  pedis. 


FiQ.  86. 
Posterior  tibial  group  of  muscles 
of  the  right  limb— postero-internal 
view.  The  gastrocnemius  is  removed. 
a,  Popliteus;  6,  Flexor  pedio  per- 
foratus;  t'.  Its  tendon;  6",  Expansion 
of  its  tendon  forming  the  cap  of  the 
hock;  c,  Flexor  pedis  perforans;  c', 
Its  tendon  ;  d,  Floxor  accessorius,  d', 
Union  of  its  tendon  with  that  of  the 
perforans. 


POSTERIOR   TIBIAL   GROUP.  251 

Belation. — Posteriorly  with  the  gastrocnemius  and  flexor 
perforatus  ;  anteriorly  with  the  tibia ;  internally  with  the  flexor 
pedis  accessorius  ;  externally  with  the  peroneus. 

Action. — To  flex  the  phalanges,  and  assist  in  extending  the 
tarsal  joint. 

FLEXOR   PEDIS  ACCESSORIUS. 

{Flexor  Obliguus — Peroneo-phalangeus.) 

(Fig.  86.  d.) 

This  muscle  is  situated  on  the  posterior  part  of  the  leg,  between 
the  popliteus  and  flexor  pedis  perforans.  It  is  fleshy,  with 
numerous  fibrous  intersections,  and  inferiorly  a  terminal  tendon. 

Origin. — From  the  external  tuberosity  of  the  tibia,  and  some- 
times slightly  from  the  fibula;  the  tendon  commences  just  above 
the  tarsal  joint,  and  passes  through  a  theca  on  its  internal  aspect. 

Insertion. — It  joins  the  tendon  of  the  flexor  perforans  at 
about  a  third  from  its  commencement. 

Relation. — Posteriorly  with  the  gastrocnemius  and  flexor 
perforatus ;  anteriorly  with  the  perforans,  the  popliteus,  and 
the  posterior  tibial  artery. 

Action. — To  assist  the  flexor  pedis  perforans. 

POPLITEUS. 

(Femoro-tibialis  Obliquus.) 

(Fig.  86.  a.) 

Situated  at  the  back  of  the  tibia,  just  below  the  stifle  joint, 
this  muscle  is  triangular  and  fleshy,  the  fibres  passing  obliquely 
downwards  and  inwards. 

Origin. — By  a  tendon  from  a  fossa  outside  the  external  con- 
dyle of  the  femur ;  it  is  attached  to  the  capsular  ligament  of  the 
stifle  joint. 

Insertion. — The  triangular  surface  on  the  supero-posterior  part 
of  the  tibia,  and  the  upper  portion  of  its  internal  border. 

Belation. — Posteriorly  with  the  gastrocnemius  and  flexor 
perforatus  ;  anteriorly  with  the  tibia,  the  capsular  ligament,  and 
the  tibial  vessels  ;  externally  with  the  flexor  pedis  perforans  and 
accessorius;  internally  with  the  biceps  rotator,  and  tibial  fascia. 
Action. — It  flexes  the  leg,  rotates  it  inwards,  and  tenses  the 
capsular  ligament  of  the  stifle  joint. 


252  MYOLOGY. 


Metatarsal  Region. 

In  this  region  we  have  the  lumbricales  and  interossei  as  in  the 
anterior  extremity,  and  also  the  extensor  pedis  brevis. 


EXTENSOR  PEDIS  BREVIS. 

(Extensor  Pedis  Accessorius.) 

(Fig.  85.  d) 

Situated  in  front  of,  and  below  the  tarsal  joint,  it  is  small  and 
triangular  in  form,  filling  up  the  space  between  the  converging 
tendons  of  the  extensor  pedis  and  peroneus. 

Origin. — From  the  infero-anterior  part  of  the  astragalus  ;  it  is 
also  attached  to  the  cuneiform  bones. 

Insertion. — It  joins  the  tendons  of  the  extensor  pedis  and 
peroneus. 

Relation. — Underneath  this  muscle  passes  the  anterior  tibial 
artery,  giving  oflf  the  perforating  pedal  branch. 

Action. — It  assists  slightly  the  extensors  of  the  foot. 


Arrangement  of  the  Fascia. 

We  have  already  seen  that  the  muscular  system  is  invested  by 
an  areblo-fibrous  covering,  which  has  been  named  the  superficial 
fascia.  This  covering  varies  very  much  in  density  in  different 
regions,  and  in  some  becomes  blended  with  the  aponeurosis  of  the 
panniculus ;  and  generally  where  the  muscles  are  braced  by  the 
fleshy  portion  of  the  latter,  the  investing  faecia  is  more  or  less 
rudimentary,  as  in  the  head  and  neck ;  it  is  with  difficulty 
demonstrable  as  a  separate  structure  in  the  latter.  The  -tunica 
abdominalis  has  been  considered  as  an  elastic  development  of  the 
investing  abdominal  fascia. 

DEEP   FASCLE. 

The  following  may  convey  a  general  idea  of  the  arrangement 
of  the  deep  or  aponeurotic  fasciae.  Each  muscle  is  more  or  less 
completely  covered  by  a  fold  of  fascia,  which  forms  a  sheath 
round  it  and  its  tendon  ;  it  then  passes  to  and  covers  another 


ARRANGEMENT   OF   THE   FASCIA.  25 S 

muscle,  and  so  on  until  it  finally  gives  oflf  an  expansion  which 
covers  the  entire  group  or  region,  becoming  firmly  attached  to 
the  skeleton,  and  usually  at  its  salient  points.  Hence  we  may 
regard  an  aponeurotic  fascia  as  a  compound  sheath,  which  con- 
tains in  its  compartments  muscles  and  their  concomitant  struc- 
tures, and  aids  the  former  in  their  action  by  passive  support  ; 
the  support  thus  afforded  is  not  always  wholly  passive,  since,  as 
we  have  seen,  some  fasciae  are  regulated  as  to  their  tension  by 
special  muscles,  the  fasciae  of  the  limbs  affording  good  examples 
of  this  arrangement. 

Some  of  the  deep  fasciae  merit  special  attention,  and  we  shall 
consider  them  in  the  order  generally  observed  in  dealing  with 
other  widely-diffused  structures — i.e.,  as  apertaining  to  the  Head, 
the  Trunk,  and  the  Limbs. 


FASCLE   OF   THE   HEAD. 

In  this  region  there  is  little  that  is  noteworthy  in  the  disposi- 
tion of  the  fascia.  It  is,  however,  much  stronger  in  the  posterior 
than  in  the  anterior  portion,  the  muscles  of  the  former  being 
separated  merely  by  folds  which  closely  resemble  ordinary  con- 
nective tissue.  The  temporal  fascia  is  the  name  given  to  a 
strong  fold  which  covers  the  temporal  fossa,  being  attached  to 
the  parietal  ridge  and  to  the  zygoma,  and  corresponding  to  the 
temporalis  and  attollentes  muscles. 


FASCIA   OF   THE   TRUNK. 

These  are  the  cervical,  dorso-lumbar,  abdominal,  and  thoracic 
fasciae. 

The  deep  fascia  of  the  cervical  region  is  better  marked  than 
the  superficial,  and  it  invests  the  muscles  in  the  typical  manner 
above  described,  becoming  attached  to  the  vertebrae.  In  the 
dorso-lumbar  region  it  is  variable,  being  thin  in  some  situations, 
but  thick  and  strong  in  others  ;  that  covering  the  postero- 
superior  part  of  the  longissimus  dorsi  is  actually  tendinous  in 
structure,  giving  origin  to  part  of  the  gluteus  maximus.  The 
dorso-lumbar  fascia  becomes  continuous  posteriorly  with  that  of 
the  gluteal  region,  and  anteriorly  with  that  of  the  external 
scapular  region. 

The  deep   abdominal  fascia  chiefly    includes  the  following 


254  MYOLOGY. 

portions  : — The  transverse,  the  iliac,  the  pelvic,  the  inguinal, 
and  the  perineal.  The  transverse  (fascia  transversalis)  is  inter- 
posed between  the  transversalis  abdominis  and  the  peritoneum, 
and  is  in  the  horse  a  very  thin  structure  ;  in  the  human 
subject,  and  in  some  other  animals,  it  is  thickened  posteriorly, 
and  attached  to  the  crural  arch.  The  iliac  fascia  (fascia  iliaca) 
covers  the  muscles  of  the  sublumbar  region,  especially  the  psoas 
magnus  and  iliacus,  which  it  enfolds  and  accompanies  to  their 
insertion.  It  is  attached  internally  along  the  tendon  of  the  psoas 
parvus  muscle,  by  which  it  is  tensed,  externally  to  the  anterior 
iliac  spine ;  anteriorly  it  becomes  very  rudimentary,  although  it 
may  sometimes  be  traced  as  far  as  the  arcuate  ligament  of  the 
diaphragm.  The  sartorius  and  cremaster  muscles  arise  partly 
from  this  fascia. 

The  pelvic  fascia  (fascia  pelvica)  is  a  strong  layer  lining  the 
pelvic  cavity,  and  covered  anteriorly  by  the  peritoneum  ;  inferiorly, 
it  splits  into  two  folds,  the  external  of  which  lines  the  sides  and 
floor  of  the  cavity,  and  is  named  the  obturator  fascia,  since  it 
covers  the  internal  muscles  of  that  name  ;  it  also  furnishes  a 
sheath  for  the  internal  pudic  vessels.  The  other  fold,  the  recto- 
vesical fascia,  is  reflected  inwards  and  posteriorly  gives  ofif  bands, 
ene  of  which  separates  the  bladder  from  the  rectum,  another 
investing  the  latter,  while  two  others  serve  as  ligaments  of  the 
bladder.  The  inguinal  and  perineal  fasciae  will  be  more  appro- 
priately described  in  a  future  section  of  the  work. 

The  thoracic  fascia  stretches  across  the  anterior  opening  of 
the  thurax,  and  is  its  anterior  boundary,  surrounding  and  bracing 
the  v.'uious  structures  which  pass  through,  and  helping  to  keep 
them  in  their  relative  positions. 

FASCIA    OF   THE    ANTERIOR    LIMB, 

These  correspond  to  the  various  regions  of  the  limb.  The 
external  scapvlar  fascia  is  very  strong  superiorly,  and  it  covers 
the  external  scapular  muscles,  giving  otf  folds  which  enclose  them. 
It  is  attached  to  the  cartilage  and  spine  of  the  scapula,  and  is 
continuous  with  the  dorso-lumbar  fascia  behind,  the  subscapular 
fascia  round  the  edge  of  the  antea-spinatus^  and  below  with  the 
brachial  fascia.  It  is  tensed  by  the  pectoralis  parvus  and  teres 
exteinus  muscles.  The  brachial  fascia  is  comparatively  thin  ; 
it  covers  and  invests  the  humeral  and  triceps  extensor  muscles. 


ARRANGEMENT    OF    THE    FASCIA.  255 

^nd  is  continued  below  by  the  antibrachial  fascia,  which  is 
exceedingly  thick  and  strong,  firmly  bracing  the  muscles  of 
the  fore-arm  ;  it  is  attached  to  the  inner  side  of  the  radius, 
to  its  distal  end  both  externally  and  internally,  and  likewise  to 
the  olecranon.  On  the  inner  aspect  of  the  limb  it  is  separable 
into  layers,  the  external  of  which  is  tensed  by  the  pectoralis 
transversus,  while  the  internal  gives  off  folds  which  pass  between 
the  muscles  and  form  sheaths  for  them,  and  is  attached  supe- 
riorly to  the  flexor  brachii  and  scapulo-ulnaris  muscles,  which 
are  its  tensors.  Inferiorly,  this  fascia  becomes  continuous  with 
the  annular  ligaments  of  the  carpus,  thus  helping  to  form  sheaths 
for  the  passage  of  the  tendons. 


FASCIA   OF   THE   POSTERIOR   LIMB. 

The  gluteal  fascia  covers  the  region  of  the  same  name,  and  is 
thick,  strong,  and  somewhat  elastic,  usually  containing  more  or 
less  fatty  matter.  It  is  continuous  anteriorly  with  the  fascia  of 
the  dorso-lumbar  region,  posteriorly  and  externally  with  the  crural 
fascia,  and  is  firmly  attached  to  the  anterior  iliac  and  the  sacral 
spines.  Its  internal  surface  gives  attachment  to  portions  of  the 
gluteus  maximus  and  externus. 

The  femoral  or  crural  fascia  surrounds  the  muscles  of  the 
thigh.  The  anterior  and  external  portions  are  known  as  the 
fascia  lata  ;  the  internal  portion  anteriorly  is  derived  from  the 
aponeurosis  of  the  obliquus  abdominis  externus;  passing  backwards, 
it  becomes  rudimentary,  and  is  replaced  posteriorly  by  connective 
tissue.  The  fascia  lata  encloses  the  triceps  cruralis,  and  exter- 
nally divides  into  two  folds,  internal  and  external ;  the  former 
passes  between  the  vastus  externus  and  triceps  abductor,  and 
accompanies  the  tendon  of  the  gluteus  externus  to  its  insertion  at 
the  trochanter  minor ;  the  external  fold  covers  the  triceps  abduc- 
tor muscle,  becoming  continuous  above  with  the  gluteal  fascia. 
The  fascia  lata  is  attached  inferiorly  to  the  patella,  and  below  is 
continuous  with  the  aponeurotic  insertion  of  the  triceps  abductor, 
and  so  with  the  tibial  fascia ;  it  is  tensed  by  its  own  muscle,  the 
tensor  fasciae  latse. 

The  tibial  fascia,  like  the  antibrachial,  to  which  it  corresponds, 
is  very  strong  and  thick,  and  covers  the  tibial  group  of  muscles, 
sending  in  folds  to  form  sheaths  for  them.  It  gives  attachment 
to  the  triceps  abductor,  biceps,  rotator,  and  gracilis  muscles,  which 


256 


MYOLOGY. 


presumably  act  as  its  tensors.  It  is  attached  to  the  crest  and 
inner  aspect  of  the  tibia,  and  also  to  the  calcaneum,  and  it  biends^ 
with  the  annular  ligaments  of  the  tarsal  joint,  assisting  in  form- 
ing sheaths  for  the  tendons.  This  fascia  is  continued  over  the 
tarsus  and  metatarsus:  becoming  somewhat  thinner  inferiorly; 
between  the  tendo-Achillis  and  the  flexor  muscles  of  the  foot  it 
is  very  strong,  giving  powerful  bands  to  the  former,  and,  near  the 
calcaneum,  helping  to  form  a  sheath  for  the  gastrocmius  tendon. 
Below  and  before  the  tendo-Achillis  it  divides  into  two  folds, 
which  assist  externally  and  internally  in  the  formation  of  the 
tarsal  sheath,  for  the  perforans  tendon ;  between  these  folds  are 
the  posterior  vessels  and  nerves  of  the  region. 


TABLE  OF  MUSCULAR  ATTACHMENTS. 

In  the  following  Table  we  enumerate  the  principal  bones  of  the 
horse,  tabulating  the  names  of  the  most  important  muscles  which 
are  attached  to  each  :- 

THE  HEAD. 


Cranial  Bones, 
occipital. 

Levator  humeri. 

Splenius. 

Compli&xus,  major  and  minor. 

Rectus    capitis    anticus,    major, 

minor,  and  lateralis. 
Rectus  capitis  posticus,  major  and 

minor. 
Obliquus  capitis  anticus. 
Stylo-hyoideus. 
Stylo-maxillaris. 
Digastricus. 

PARIETAL. 
Temporalis. 

FRONTAL. 
Levator  labii  superioris  alseque  nasi. 

TEMPORAL. 
Trachelo-mastoide  us. 


Levator  humeri 

Temporalis. 

Mastoido-auricularis. 

SPHENOID. 
Rectus  capitis  anticus,  major  and 

minor. 
Pterygoideus,    extemus    and    in- 

ternus. 

Facial  Bones, 
superior  maxilla 

Panniculus  carnosus. 

Masseter. 
Buccinator. 
Nasal  is  longus. 
Dilatator  naris  lateralis. 

PREMAXILLA. 
Dilatator  naris  inferioris. 
Depressor  labii  superioris. 


MUSCULAH    ATTACHMENTS. 


257 


NASAL. 
Dilatator  naris  sucerioris. 

LACHRYMAL. 

Orbicularis  palpebrarum. 
Lachrymal  is. 

MALAR. 
Nasalis  longus. 

PALATINE. 
Pterygoideus  internus. 

INFERIOR   MAXILLA. 
Masseter. 
Temporalis. 

Pterygoideus,  externus  and  interixus. 
Sterno-maxillaris. 
Stylo-maxillaris. 


Buccinator. 

Levator  labii  inferioris. 

Depressor  labii  inferioris. 

Mylo-hyoideus. 

Genio-hyoideus. 

Digastricus. 


/ 


HYOID    SERIES. 
Sterno-thyro-hyoideus. 
Subscapulo-hyoideus. 
Myo-hyoideus. 
Genio-hyoideus. 
Hyoideus  magnus. 
Hyoideus  parvus. 
Hyoideus  transvei-sus. 
Stylo-hyoideus. 

Certain  muscles  of  the  tongue^ 
pharynx,  larynx,  and  soft  palate 
are  not  enumerated  here. 


XHii:  TRUNK. 


Cervical  Vertebs^c. 

ATLAS. 

Levator  humeri. 

Splenius. 

Trachelo-mastoideus. 

Obliquus   capitis,    anticxis    and 

posticus. 
Rectus   capitis   ahticus,    major, 

minor,  and  lateralis^ 
Longus  colli. 

DENTATA. 

Longus  colli. 

Levator  humeri. 

Intertransversalis  collL 

Obliquus  capitis  posticus. 

Complexus  minor. 

Rectus  capitis  posticus  major. 

Spinalis  colli. 

SEGMENTS  3  TO  7. 

Longus  colli. 


Rectus  capitis  anticus  major  (3rd 

to  5th). 
Intertransversalis  colli. 
Transversalis  costarum  (7  th) 
Levator  humeri  (3rd  and  4th). 
Splenius  (3rd  to  5th). 
Serratus  magnus. 
Spinalis  colli. 
Trachelo-mastoideus. 
Compl'^xus  major. 
Longissimus  dorsi  (4th  to  7th). 

DORSAL    VERTEBRA. 

Splenius  ) 

Complexus  major  )  v  ^^      /* 
Trachelo-mastoideus  (first  2). 
Trapezius  dorsalis  (3rd  to  11th). 
Latissimus  dorsi  (last  15). 
Superficialis  costarum  (last  17). 
Rhomboideus  brevis  (2nd  to  7th), 
Longissimus  dorsi. 

S 


258 


MYOLOGY. 


fSemispinalis  dorsi. 
Levatores  costarum. 
Longus  colli. 
Psoas  parvus  (last  3). 
Psoas  magnus  (last  2). 

LUMBAR    VERTEBRA. 
Xiatissimus  dorsi. 
Superficialis  costarura  (first  3). 
Longissimus  dorsi. 
Seniispinalis  lumborum. 
Psoas  magnus. 
Psoas  parvus. 
Quadratus  lumborum. 
Intertransversalis  lumborum. 
Transversalis  abdominis. 
Crura  diaphragmatica. 

SACRUM. 
Longissimus  dorsi. 
Seraispinalis  lumborum. 
Gluteus  externus. 
Gluteus  maximus. 
Triceps  abductor  feraoris. 
Biceps  rotator  tibialis. 
Pyriformis. 
.All  the  coccygeal  muscles. 

COCCYX, 
j^ll  the  coccygeal  muscles. 
The   Compressor   coccygis    to    th( 
.first  2  segments. 


RIBS  AND  COSTAL  CARTILAGES. 

Scalenus  (1st). 

Superficialis  costarum  (last  14). 

Longissimus  dorsi  (last  16). 

Transversalis  costarum. 

Serratus  magnus  (first  8). 

Lateralis  sterni  (1st). 

Triangularis  sterni  (2nd  to  8th). 

lutercostales. 

Levatores  costarum. 

Obliquus  abdominis  externus  (last 

14). 
Transversalis  abdominis  (last  10). 
Obliquus  abdominis  \ 

internus.  ^  (cartilages). 

Pv,ectus  abdominis.     / 
Diaphragm  (last  12). 
Psoas  magnus  (last  2). 
Quadratiis  lumborum  (last  3). 

STERNUM. 
Panniculus  carnosus. 
Sterno-maxillaris. 
Sterno-thyro-hyoideus, 
The  four  Pectorales. 
Lateralis  sterni. 
Triangularis  sterni. 
Rectus  abdominis. 
Transversalis  abdominis. 
Diaphragm. 


Ti-apezius. 

Levator  humeri. 

Antea-spinatus. 

Postea-spinatus. 

Postea-spiuatus  minor. 

Teres  externus. 

Rhomboideus,  longus  and  brevis 

Serratus  magnus. 

^ubscapularis. 


PECTORAL  LIMB. 

Pectoralis  parvus. 
Scapulo-ulnaris. 
Caput  magnum. 
Scapulo-humeralis  posticus. 
Teres  internus. 
Coraco-humeralis. 
Flexor  brachii. 


HUMERUS. 

Antea-spinatus. 
Postea-spinatus. 


MUSCULAR    ATTACHMENTS. 


25» 


Postea-spinatus  minor. 

Subscapularis. 

Scapulo-humeralis  posticus, 

Pectoralis,  magnus  and  anticus. 

Panniculus  carnosus. 

Teres,  externus  and  intern  us. 

Coraco-humeralis. 

Humeralis  obliquus. 

Caput  medium  and  parvum. 

Anconeus. 

Latissimus  dorsi. 

Levator  humeri. 

Extensor  metacarpi  magnus. 

Extensor  pedis. 

Three  Flexores  metacarpi. 

Flexor,  perforans  and  perforatus. 

RADIUS. 
Flexor  brachii. 
Humeralis  obliquus. 
Extensor   metacarpi,  magnus  and 

obliquus. 
Extensor  pedis. 
Extensor  suffraginis. 
Radialis  accessorius. 


UINA. 
Triceps  extensor  brachii. 
Scapulo-ulnaris. 
Anconeus. 

Flexor  metacarpi  medius. 
Ulnaris  accessorius. 
Humeralis  obliquus. 
Extensor  suffraginis, 

TRAPEZIUM. 
Flexor    metacarpi,   extenius    and 
medius. 

METACARPUS. 

LARGE    BONE. 

Extensor  metacarpi  magnus. 

EXTERNAL   BONE. 

Flexor  metacarpi  externus, 

INTERNAL  BONE. 

Extensor  metacarpi  obliquus. 
Flexor  metacarpi  internus, 

DIGIT. 
Extensor  pedis  (three  phalanges). 
Extensor  suffraginis  (1st  phalanx). 
Flexor  perforatus  (2nd  phalanx). 
Flexor  perforans  (3rd  phalanx). 


PELVIC  LIMB. 


OS  INNOMINATUM. 

Longissimus  dorsi. 

Compressor  coccygis. 

Four  Abdominales. 

Three  Glutei. 

Tensor  fasciae  latae. 

Rectus  femoris. 

Rectus  parvus. 

Obturator,  externus  and  internus, 

Pyriformis. 

Two  Gemelli. 

Iliacus. 

Psoas  parvus. 

Quadratus  lumborum. 

Gracilis. 


Sartorius. 

Pectineus. 

Triceps  adductor  femoris. 

Triceps  abductor  femoris. 

Biceps  rotator  tibialis. 

Ischio-femoralis. 

FEMUR. 
Psoas  magnus. 
Iliacus. 
Three  Glutei. 

Obturator,  externus  and  internus: 
Pyriformis. 
Two  Gemelli. 
Tensor  fasciae  latae. 
Vastus,  externus  and  internus. 


260 


COMPARATIVE   MYOLOGY. 


Rectus  pai'vus. 

Crureus. 

Pectineus. 

Triceps  adductor  femoris. 

Triceps  abductor  femoris.  * 

Ischio-femoralis. 

Gastrocnemius. 

Flexor  perforatus. 

Extensor  pedis. 

Flexor  metatarsi. 

Popliteus. 

TIBIA. 
Sartorius. 
Gracilis. 

Triceps  abductor  femoris. 
Biceps  rotator  tibialis. 
Flexor  metatarsi. 
Plantaris, 
Popliteus. 
Flexor  perforans. 
Flexor  accessorius. 


FIBULA. 
Peroneus, 
Flexor  perforans. 

PATELLA.  ^ 

Tensor  fasciae  latse. 
Quadriceps  cruralis. 
Triceps  abductor  femoris. 

TAESUS. 

CALCANEUM. 

Gastrocnemius. 

CUBOID  AND  SMALL  CUNEIFORM, 

Flexor  metatarsi. 

METATARSUS. 
LARGE    BONE. 

Flexor  metatarsi. 

DIGIT. 
Extensor  pedis  (three  phalanges). 
Flexor  perforatus  (2nd  phalanx). 
Flexor  perfoi-ans  (3rd  phalanx). 


COMPARATIVE   MYOLOGY. 

A.N  extensive  section  devoted  to  this  subject  would  be  somewhat  out  of  place 
in  an  ordinary  class-book ;  •  therefore  for  fuller  descriptions  and  details  the 
student  must  have  recourse  to  exhaustive  works  of  reference,  or,  what  is  still 
better,  to  his  own  dissections  and  observations,  bearing  in  mind  the  typical 
branch  of  the  subject.  We  shall  endeavour  to  point  out  where  the  more 
important  muscles  of  the  domesticated  animals  present  features  which,  for  our 
purpose,  are  worthy  of  comparison  with  those  of  the  selected  type  ;  and  in 
this  attempt  we  observe  very  generally  the  same  sequence  as  to  regions  and 
groups  that  we  have  adopted  in  describing  the  muscles  of  the  horse. 


RUMINANTIA. 

Subcutaneous  Region. 

The  panniculus  carnosus  in  the  cervical  region  is  mostly  aponeurotic ;  a 
muscle  which  resembles  the  sterno-niaxillaris  of  the  horse  is  sometimes 
regarded  as  constituting  its  inferior  tieshy  portion.  In  the  head  it  resemblefi 
that  of  the  horse,  but  there  is  a  fleshy  expansion  in  the  frontal  region — the 
so-called  frontalis  muscle — which  is  apparently  a  part  of  the  panniculus.  In 
the  trunk  there  is  no  very  important  deviation  from  the  arrangement  already 
■described. 


RUMINANTIA THE    TRUNK.  261 


The  Head. 


In  the  ruminant  the  palatine  ridges  being  closer  together,  the  pterygoid 
inuscles  originate  nearer  to  the  median  line  of  the  head,  and  thus  produce  more 
lateral  motion  in  the  lower  jaw  than  there  is  in  that  of  the  horse.  There  is 
no  digastric  muscle  in  the  domesticated  animals  other  than  the  horse,  the 
muscle  representing  it  having  only  one  belly ;  in  the  ox  it  is  joined  to  its 
fellow  on  the  other  side  by  a  small,  square,  transverse  muscle.  The  massetcr 
and  temporalis  are  both  less  strong.  Passing  from  the  root  of  the  horn  core  to 
the  upper  edge  of  the  orbital  fossa  is  a  flat  thin  muscle,  the  frontalis,  which 
blends  with  the  external  levator  of  the  evelid  ;  it  is,  perhaps,  a  portion  of  the 
panniculus.  The  levator  labii  superioris  alceqne  nasi  is  not  present  in  the 
smaller  ruminants,  and  in  the  ox  it  differs  in  that  the  anterior,  instead  of  the 
posterior  division,  covers  the  dilatator  naris  lateralis,  and  that  it  covers  the 
nasalis  longus  as  well.  Two  accessory  muscles  arise  in  common  with  the  last 
named,  and  go  to  the  upper  lip.  The  dilators  of  the  nostril,  except  the  lateralis, 
are  wanting.  The  zygomaticus  has  a  long  tendon  of  origin  reaching  up  to  the 
zygoma.    The  long  tendon  of  insertion  of  the  depressor  labii  inferioris  is  wanting. 

The  hyoideus  magnus  has  a  long  tendon  of  origin,  and  it  forms  no  sheath, 
there  being  no  median  digastric  tendon.  The  lachrymalis  is  closely  blended 
above  with  the  anterior  border  of  the  orbicularis  palpebrarum,  and  is  more 
developed  and  thicker  than  in  the  horse. 

The  Trunk. 

The  muscle  which  would  appear  to  correspond  to  the  sterno-maxillaris  of 
the  horse,  is  considered  by  Chauveau  as  representing  the  inferior  fleshy  band  of 
the  panniculus  carnosus  ;  it  is  attached  superiorly,  not  to  the  angle  of  the 
maxilla,  but  to  the  fascia  of  the  masseter  muscle,  and  sometimes  it  may  be 
traced  to  the  zygoma.  This  view  being  taken,  the  sterno-maxillaris  finds  its 
representative  in  the  sterno-suboccipitalis,  a  muscle  which  becomes  inserted  to 
the  basi-occipital  bone  in  company  with  a  tendon  of  the  levator  humeri  The 
sterno-thyro-Tiyoideiis  is  larger  than  in  the  horse,  and  not  digastric.  The  rectiis 
capitis  a^iticus  major  is  covered  by  the  trachelo-atloideus,  a  flat  muscle  joining 
the  atlas  inferiorly  to  some  of  the  succeeding  vertebrae. 

The  levator  humeri  is  attached  anteriorly  to  the  mastoid  process,  to  the 
posterior  surface  of  the  occipital  bone  and  the  ligamentum  nuchse,  to  the  basi- 
occipital  bone  together  with  the  sterno-suboccipitalis,  and  to  the  wing  of  the 
atlas  by  a  tendon  separate  from  that  of  the  splenius  and  trachelo-mastoideus. 
In  ruminants  the  splenius  is  very  .small ;  in  the  camel  it  is  stated  by  Cuvier  to 
be  non-existent,  or  at  least  so  small  as  to  escape  observation. 

In  the  costal  and  dorso-lumbar  regions  there  is  little  that  merits  comparison ; 
Ave  may,  however,  note  that  the  trapezius  and  serratus  magnus  are  largely 
developed ;  also  that  the  intercostales  and  levatores  costarum  of  course  vary 
in  numbei-  with  the  ribs.  The  pectoralis  antictis  is  small,  and  blended  con- 
siderably with  the  transversus. 

The  abdominal  tunic  is  large  and  very  thick,  its  development  being  always 
proportional  to  the  magnitude  of  the  abdominal  viscera  The  linem  transverse^ 
'Oi  the  rectus  abdominis  are  very  well  marked.     The  obliquus  internus  is  large. 


262 


COMPARATIVE    MYOLOGY. 


and  fills  up  the  space  between  the  ilium,  the  last  rib,  and  the  lumbar  verte- 
bra;.    The  fascia  t ran sver sails'  is  better  marked  than  in  the  horse.     In  the 

muscles  of  the  sublumbar  region, 
no  comparison  is  necessary. 

The  diaphragm  in  ruminants  is 
thick  and  strong,  being  propor- 
tionate to  the  weight  of  the  ab- 
dominal viscera,  which  it  is  its 
function  to  compress  and  force 
backwards.  The  crura  are  both 
long  and  large,  and  the  periphery 
is  attached  more  anteriorly  than 
in  the  horse  In  the  camel  the 
diaphragm  usually  contains  a 
small  bone. 

Pectoral  Limb, 

The  extensors  of  the  metacarpus 
are  disposed  as  in  the  horse,  ex- 
cepting that  the  tendou  of  the 
obliquus  is  inserted  to  the  great 
metacarpal  bone.  The  extensor 
pedis  is  divided  throughout  its 
length,  giving  rise  to  an  external 
muscle,  the  extensor  communis 
digitorum,  and  an  internal  one^ 
the  extensor  proprius  internus,  the 
former  being  rather  larger  than 
the  latter.  The  tendons  of  these 
muscles  run  down  the  metacarpus 
in  company,and  at  the  commence- 
ment of  the  digits  that  of  the 
extensor  communis  bifurcates,  a 
portion  being  inserted  to  the 
pyramidal  process  of  each  distal 
phalanx.  The  tendon  of  the 
extensor  proprius  internus  re 
ceives  slips  Irom  the  suspensory 
ligament  about  the  middle  of  the 
first  phalanx,  and  is  attached  to 
the  median,  and  outer  surface  of 
the  internal  distal  phalanges.  The 
extensor  suffraginis  becomes,  in 
thQr\xm.\fia.niyi\iQ  extensor  proprius 
externus,  diflfering  from  the  former 
muscle  of  the  horse  in  being  thicker  and  stronger,  and  in  being  inserted  in  the 
same  manifer  as  the  internus.     Tliese  three  muscles  are  all  extensors,  but  the 


Fio.  ST. 
Tendons  and  ligaments  of  left  anterior  extremity  of 
Ox,  viewed  from  external  side,  a.  Flexor  perforatus 
tendon  ;  a',  Its  superficial ;  a",  Its  deep  branch  ;  6,  In- 
terosseus  metacarpeus  ;  c.  Flexor  perforans  tendon  ; 
d-d",  e-e'",  Superior  suspensory  ligament  and  attach- 
ments ;  d,  anterior  division  ;  d',  Its  superficial  branch, 
blending  at  d"  with  extensor  proprius  tendon  ;  e,  Deep 
branch  of  posterior  divisiou  ;  e',  e".  Branches  forming 
superior  ligaments  of  small  claw  ;  e'",  Inferior  liga- 
ment of  small  claw;  />_ Common  annular  ligament; 
0,  o',  Superior  and  inferior  special  annular  ligaments  ; 
It.  Interdigital  ligament ;  i,  i'.  Tendon  of  the  extensor 
proprius  externus. 


OMNIVORA SUBCUTANEOUS    REGION.  263 

communis  is  also  an  approximator,  ■while  the  proprii  are  divertors  or  expansoi-s 
of  the  digits.  The  flexor  perforatus  is  a  double  muscle,  but  unites  to  form  a 
single  tendon,  which  divides,  and  each  part  behaves  as  the  single  portion  in 
the  horse,  being  however  assisted  in  the  formation  of  the  sheaths  for  the  per- 
forans  tendons  by  two  strong  slips  from  the  suspensory  ligament,  which  corre- 
spond to  the  check  ligament.  In  effect  the  check  ligament  may  be  said  to  be 
attached  in  the  ruminant  to  the  perforatus  tendon  only.  The  tendon  of  the 
flexor  perforans  also  divides,  the  two  parts  passing  through  the  sheaths  formed 
as  above  described,  and  terminating  in  a  similar  manner  to  that  of  the  horse,, 
becoming  however  blended  with  the  plantar  cushion  of  the  foot,  and  the 
inferior  interdigital  ligament. 

Pelvic  Limb. 

The  gluteus  externus  is  intimately  blended  with  the  triceps  abductor.  The 
maximus  is  nearly  covered  by  the  above  compound  muscle  and  that  of  the 
fascia  lata,  and  is  smaller  than  in  the  horse,  while  the  internus,  on  the  other 
hand,  is  larger.  The  tensor  fascice  latcs  and  triceps  abductor  become  firmly 
united  over  the  region  of  the  trochanter  major,  the  former  muscle  being  largely 
developed,  while  the  latter  has  no  femoral  attachment.  The  rectus  parvus  is 
wanting. 

The  biceps  rotator  tibialis  has  no  sacral  origin.  There  is  no  pyriformis 
muscle,  but  a  muscle  has  been  described,  pursuing  a  similar  course  outcide  the 
pelvis,  .and  so  far  corresponding  to  it.  The  tendon  of  the  obturator  internus 
passes  through  the  obturator  foramen. 

The  fibrous  portion  of  the  flexor  metatarsi,  and  the  extensor  pedis  of  the  horse 
have  in  the  ox  a  common  tendon  of  origin,  giving  rise  to  three  large  muscles 
of  which  the  external  one  is  the  extensor  communis  digitorum,  and  the  internal 
the  extensor  proprius  internus,  the  tendons  of  these  two  terminating  as  in  the 
anterior  limb.  The  third  muscle,  situated  before,  and  somewhat  to  the  inner 
side  of  the  others,  is  a  flexor  of  the  metatarsus,  and  represents  the  fibrous  portion 
of  the  flexor  metatarsi  in  the  horse,  forming  a  sheath  or  ring  through  which 
passes  the  tendon  of  the  tibialis  anticus,  a  muscle  rejjresenting  the  fleshy  portion 
of  the  same. 

The  peroneus  becomes  the  extensor  proprius  externus,  and  is  attached  distally 
as  in  the  fore  limb.  A  muscle  which  has  no  representative  in  the  horse  is  one 
which  has  been  named  the  peroneus  longus  lateralis.  It  arises,  deeply  seated, 
from  the  external  part  of  the  head  of  the  tibia,  and  terminates  in  a  long  slender 
tendon  which  winds  obliquely  over  that  of  the  proprius  externus  at  the  tarsal 
joint,  and  after  pursuing  a  tortuous  course  round  the  outside  of  the  joint,  is 
inserted  to  the  small  cuneiform  and  metatarsal  bones. 

The  flexor  perforatus  of  the  ruminant  is  thicker  in  the  fleshy  portion  than  that 
of  the  lioise,  and  the  flexor  perforans  is  more  clearly  divisable  into  two  parts. 

OMNIVORA. 
Subcutaneous  Region. 
In  the  hog  the  cervical  portion  of  the  panniculus  carnosus  is  double,  one  part 
arising  from  the  cariniform  cartilage  of  the  sternum,  and  the  other  from  the 


264  COMPARATIVE    MYOLOGY. 

external  scapular  region.    Anteriorly  the  parts  unite,  and  the  muscle  expands 
over  the  face,  joining  its  fellow  of  the  opposite  side. 

The  Head. 
The  levator  labii  superioris  alceque  nasi,  dilatator  naris  transversus,  and  lachry- 
malis  are  wanting,  but  the  nasalis  longus  is  well  developed.     The  retrahens 
exlernus  has  two  tendons  of  insertion,  one  proceeding  to  the  conchal,  the  other 
to  the  scutiform  cartilage. 

The  Trunk. 

The  inferior  portion  of  the  levator  humeri  is  attached  by  one  tendon  to  the 
occipital  protuberance,  and  by  a  second  to  the  mastoid  crest,  the  superior 
portion  going  to  the  wing  of  the  atlas.  ^ 

The  sterno-thyroideus  is  double,  having  two  attachments  to  the  thyroid 
cartilage.  The  longus  colli,  instead  of  being  a  single  muscle  as  in  the  horse,  is 
separable  into  right  and  left  portions.  The  scalenus  extends  far  backwards, 
usually  reaching  the  third  rib. 

In  the  costal  region  we  have  merely  to  note  that  the  trapezius  is  largely 
developed  ;  the  latissimus  dorsi  is  also  large,  and  presents  digitations  by  which 
it  becomes  attached  to  the  ribs  it  covers. 

The  pectoral  muscles  resemble  those  of  the  ox.  In  the  dorso-lumbar  region 
we  find  that  the  longissimus  dorsi  is  divisible  into  a  transverse  and  a  costal 
portion. 

The  abdominal  tunic  is  a  mere  fold  of  cellulo-fibrous  membrane,  while  the 
obliquus  externus  presents  a  large  fleshy,  and  a  small,  or  rather  narrow, 
aponeurotic  portion.  In  the  sublumbar  region  the  muscles  of  the  omnivora, 
like  those  of  the  ruminants,  present  no  features  worthy  of  comparison  with 
those  of  the  horse  ;  the  diaphragm  also  calls  for  no  special  comment. 

Pectoral  Limb. 

The/ea;or  brachii  at  its  insertion  gives  off  a  tendon  which  passes  to  the  ulna, 
and  is  attached  to  the  lower  part  of  the  olecranon,  and  close  by  is  attached 
another  slip  from  the  humeralis  obliquus.  The  coraco-humeralis  is  short,  very 
tendinous,  and  consists  of  only  one  portion,  which  is  inserted  just  above  the 
insertion  of  the  teres  internus.  The  scapulo-ulnaris  is  continuous  with  the 
latissimus  dorsi.  The  extensor  metacarpi  magnus  is  inserted  to  the  inner  large, 
the  obliquus  to  the  inner  small  metacarpal  bone.  The  extensor  communis  tendon 
divides  into  four  parts,  one  being  attached  to  either  distal  phalanx  ;  and  the 
extensor  proprius  internus  tendon  bifurcates,  and  goes  to  the  distal  phalanges  of 
the  two  inner  digits,  the  proprius  externus  joining  the  two  outer  ones  in  a 
similar  manner.  The  fiexor  pedis  perforatus  is  double,  both  as  to  its  fleshy 
portion  and  its  tendon  ;  a  part  becomes  inserted  to  the  median  phalanx  of  each 
of  the  large  digits,  while  the  tendon  of  the  flexor  perforans  divides  into  four 
parts,  one  being  inserted  to  each  distal  phalanx. 

In  the  metacarpal  region  there  are  four  interossei  or  interosseous  palmar 
muscles,  which  arise  superiorly  from  the  back  of  the  metacarpal  bones  and 
ligaments,  and  terminate  each  in  two  small  sesamoid  tendons,  which  afterwards 


CARNIVORA THE    TRUNK.  265 

-wind  round  to  the  front  of  the  bone,  and  join  the  chief  extensor  tendon  of  theLv 
own  digit.  These  muscles  are  the  analogue  of  the  svspensory  ligament  in  the 
horse  and  ox,  as  they  perform  a  similar  function.  A  single  large  lumbricalis 
joins  the  flexor  perforans  tendon  of  the  internal  digit  to  the  extensor  proprius 
tendon  of  the  same  ;  and  on  the  outside  another  muscle  runs  from  the  carpo- 
metacarpal ligament  to  the  extensor  proprius  tendon  of  the  outer  small  digit, 
i-egarded  by  M.  Chauveau  as  the  representative  of  the  flexor  brevis  minimi 
■digiti  of  the  dog  or  the  human  subject. 

Pelvic  Limb. 

In  the  gluteal  and  femoral  regions  the  muscles  resemble  those  of  the 
ruminant ;  the  adductor  magnus  and  biceps  rotator  have  however  a  very  slight 
attachment  to  the  coccyx.  The  tendon  of  the  extensor  communis  digitorum 
<livides  into  four,  a  slip  going  to  each  digit,  those  of  the  extensores  proprii  each 
into  two,  attached  to  their  two  respective  digits.  The  peroneus  longus  is  inserted 
to  the  head  of  the  internal  metatarsal,  and  the  tibialis  anticus  to  the  cuneiform 
bones.  The  flexor  perforatus  tendon  bifurcates,  and  goes  to  the  two  great  digits, 
■while  that  of  the  perforans  divides  into  four,  becoming  inserted  to  all  the  digits. 
In  the  metatarsal  region  we  find  the  extensor  pedis  brevis  attached  by  a  divided 
tendon  to  the  extensor  tendons  of  the  great  digits,  and  sometimes  to  that  of  the 
outer  one  also.  There  are  four  interossei  which  resemble  those  of  the 
juetacarpus. 

CARNIVORA. 
Subcutaneous  Region. 

In  the  dog  the  fleshy  portion  of  the  panniculus  carnosus  is  prolonged  over 
the  haunch,  and  united  to  its  fellow  in  the  median  line  of  the  dorso-lumbar 
region.  The  cervical  portion  resembles  that  of  the  hog,  but  is  more  developed, 
■especially  the  superior  part,  which  springs  from  the  scapular  region  ;  it  covers 
the  parotid  gland,  blends  with  the  abduc«ns  muscle,  and  meets  its  fellow  in  the 
median  line  of  the  face.     The  panniculus  is  very  well  developed  in  the  felidse. 

The  Head. 
The  sygomaticus  is  continuous  posteriorly  with  the  attollens  anticus.  The 
levator  labii  superioris  is  single,  having  no  nasal  branch.  The  nasalis  longus 
joins  the  dilatator  naris  lateralis,  and  together  they  proceed  to  the  external 
aspect  of  the  nostril  and  upper  lip  ;  the  other  dilators  of  the  nostril  aro.  absent. 
The  orbicularis  oris  and  buccinator  are  very  rudimentary. 

The  Trunk. 
The  levator  humeri  is  similar  to  that  of  the  hog,  and  the  clavicle,  when  present, 
is  found  related  to  the  infero-internal  aspect  of  its  lower  portion.  The  sterno- 
maxillaris  is  represented  by  the  sterno-mastoideus ;  the  subscapulo-hyoideus  is 
wanting,  while  the  sterno-thyro-hyoideus  arises  from  the  first  costal  cartilage, 
-and  is  not  digastric.  The  scalenus  passes  further  back  than  in  the  hog, 
isometimes  reaching  the  eighth  rib,  and  the  longus  colli  is  separable  into  a 
Tight  and  left  portion. 


^Zbb  COMPARATIVE    JilTOLOGT. 

Tlie  remarks  made  regarding  the  costal,  dorso-lumbar,  and  abdominat 
muscles  of  the  hog  are,  for  the  most  part,  applicable  here.  In  the  pectoral 
region  also  there  is  little  to  call  for  remark,  unless  it  be  that  the  transversus 
and  parvus  are  very  small  and  thin.  The  following  features  presented  by  the 
muscles  of  the  sub-lumbar  region  should  be  noted.  The  quadratus  lumbomm 
attains  its  maximum  of  relative  size  in  the  dog,  and  with  it  is  blended  the 
psoas  farviisj  the  psoas  magnus,  smaller  and  shorter  than  the  parvus,  becomes 
so  blended  posteriorly  with  the  iliacus  that  they  may  almost  be  regarded  as 
one  muscle.     Neither  of  the  psoe  muscles  project  into  the  thoracic  cavity. 

Pectoral  Limb. 

The  scapular  and  brachial  muscles  are  large,  corresponding  to  the  develop- 
ment of  the  bones.  Placed  before  the  teres  externus  is  a  distinct  acromio- 
humcralis  muscle.  The  antea  and  postea  spinati  have  each  only  one  tendon  of 
insertion,  that  of  the  former  going  to  the  external  humeral  trochanter.  The 
coraco-humeralis  B-udi  flexor  hrachii  resemble  those  of  the  hog,  the  former  being- 
short,  and  inserted  just  above  the  insertion  of  the  teres  internus. 

The  antibrachial  region  includes  some  muscles,  the  consideration  of  whicii  is 
of  importance.  The  tendon  of  the  extensor  metacarpi  magnus  divides,  and  is 
attached  to  the  heads  of  the  first  and  second — i.e.,  the  two  inner  metacari)ul 
bones — while  the  extensor  obliq^ius  is  inserted  to  the  metacarpal  element  of  the- 
pollex  or  thumb.  The  extensor  communis  digitorum  has  a  tendon  divided  into 
four  parts,  a  part  going  to  each  distal  phalanx,  while  the  extensor  proprius 
tendon  is  trifurcated  and  attached  to  the  three  outer  distal  phalanges.  The 
flexor  perforatus  tendon  divides  into  four,  that  of  the  perforans  into  five  parts, 
the  first  being  attached  to  the  median  phalanges  of  the  four  principal  digits, 
the  other  to  the  distal  phalanges  of  all  the  digits.  The  ulnaris  and  radialis 
accessorii  are  present.  The  extensor  pollicis  et  indicis  arises  with  the  extensor 
metacarpi  obliquus  on  the  outer  aspect  of  the  radius  ;  its  tendon  accompanies 
that  of  the  extensor  commu.nis  through  its  sheath,  bifurcates,  and  is  inserted 
to  the  pollex  and  first  digit. 

The  following  muscles  occur  in  the  antibrachial  region,  and  are  the  intrinsic 
rotators.  The  supinator  longus,  a  very  delicate  band,  arises  internally  along 
with  the  extensor  metacarpi  magnus,  and  is  inserted  to  the  inner  diatal 
extremity  of  the  radius  ;  in  'the  dog  its  action  as  a  supinator  is  almost  nil. 
The  supinator  brevis  is  a  short  radiating  muscle,  covering  the  elbow  joint  in 
front ;  it  arises  from  the  outer  distal  end  of  the  humerus  and  lateral  ligament, 
and  is  inserted  to  the  anterior  and  inner  parts  of  the  head  of  the  radius.  It 
supinates  the  extremity — i.e.,  it  tends  to  turn  the  anterior  aspect  outwards. 
The  pronator  teres  is  a  short,  thick  muscle,  arising  from  a  small  process  on  the 
internal  epicondyle,  and  becoming  inserted  to  the  inner  border  of  the  radial 
shaft,  at  about  a  third  from  its  head  ;  it  rotates  the  extremity,  opposing  the 
supinator.  The  pronator  quadratus  is  deeply  seated  under  the  flexor  group  of 
muscles  ;  it  extends  almost  from  the  elbow  joint  to  the  carpus,  and  joins  the 
radius  to  the  ulna,  its  fibres  passing  directly  from  one  bone  to  the  other ;  it 
acts  as  a  pronator. 

There  are  fifteen  muscles  in  the  metacarpal  region  of  the  dog,  all  of  whicli 


CAENIVORA PELVIC    LTMB,  267 

are  situated  pofcteriorly,  and  for  the  mosi  pai-t  covered  by  the  flexor  tendons. 
All  the  muscles  of  the  human  hand  are  represented,  excepting  the  intcrossei 
metacarpei,  o?  >Thich  there  is  in  the  dog  only  on?  set,  the  palmares j  they  are 
four  in  number,  and  disposed  in  the  same  way  as  in  the  hog.  The  himhncales 
are  exceedingly  slender,  and  situated  between  the  branches  of  the  perforans 
tendon,  from  which  they  arise  ;  they  are  continuea  by  delicate  tendons,  whose 
attachment  is  uncertain  ;  they  may  be  traced  sometimes  to  the  extensor 
tendons  of  the  three  outer  digits  ;  their  use  is  obscure.  Connected  wdth  the 
pollex  are  three  comparatively  rudimentary  muscles — an  abductor,  an  adduc- 
tor, and  a  flexor.  The  abductor  brevis  pollicis  is  a  very  small  muscle,  directed 
downwards  and  outwards  ;  arising  from  the  posterior  carpal  ligament,  it  is 
inserted  to  the  metacarpal  element  of  the  pollex,  which  it  abducts  and  also 
flexes.  The  opponens  jjollicis,  placed  below  and  beneath  the  last,  is  large  in 
the  human  subject,  but  very  rudimentary  in  the  dog.  It  has  attachments 
similar  to  those  of  the  last-named  muscle,  bvit  is  inserted  more  to  the  inside  ; 
it  is  an  adductor,  opposition  of  the  thumb  being  impossible  in  the  dog.  The 
flexor  brevis  pollicis  is  rather  longer  than  the  preceding  muscle,  but  very 
slender ;  it  arises  also  from  the  posterior  carpal  ligament,  and  is  inserted  to 
the  proximal  phalanx  of  the  pollex,  of  which  it  is  the  chief  flexor.  The 
■adductor  indicis  is  a  long  prismatic  muscle,  situated  in  the  depression  between 
the  two  interossei ;  arising  from  the  posterior  carpal  ligament,  it  is  inserted  to 
the  proximal  phalanx  of  the  index  or  first  digit,  at  its  supero-ihtemal  part. 

Like  the  pollex,  the  outer  digit  has  three  special  muscles,  an  abductor,  an 
adductor,  and  a  flexor.  The  abductor  minimi  digiti  is  situated  outside  and 
behind  the  outer  metacarpal  bone;  it  arises  from  the  trapezium,  and  is 
inserted  by  a  long  tendon  to  the  supero-external  part  of  the  proximal  phalanx 
of  the  outer  digit.  As  its  name  implies,  it  is  an  abductor.  The  adductor 
(opponens)  minimi  digiti,  long  and  flat,  arises  close  by  the  adductor  indicis, 
passes  downwards  and  outwards,  and  its  tendon  is  inserted  as  that  of  the 
abductor  muscle,  but  to  the  inside  of  the  bone ;  it  adducts  the  digit.  The 
flexor  minimi  digiti  is  placed  on  the  inner  side  of,  and  below  the  abductor  of 
the  same  digit.  Triangular  and  flat  in  form,  it  arises  from  the  inferior  unci- 
form ligament,  joining  the  tendon  of  the  abductor.  The  palmaris  brevis,  or 
cutaneous  palmar,  is  a  thick  and  rounded  semimuscular  mass,  situated  behind 
and  below  the  carpus,  adhering  intimately  to  the  skin,  and  being  deeply 
attached  to  the  fascia  of  the  subjacent  muscles. 

In  the  felidce  the  claw  is  retracted  by  a  ligament  of  yellow  elastic  tissue. 
"  The  apparatus  for  the  retraction  of  the  ungual  phalanges  is  so  well  developed 
that  the  claws  are  completely  retracted  within  sheaths  of  the  integument,  when 
the  animal  does  not  desire  to  use  them.  To  this  end  the  elastic  ligaments  are 
very  strong,  and  the  median  phalanx  is  excavated  in  order  to  allow  of  the 
lodgment  of  the  retracted  phalanx  on  one  side  of  it." — (Huxley.) 

Pelvic  Lemb. 

The  gluteus  externus  is  very  large,  the  maximus  comparatively  small ;  the 
latter  does  not  extend  before  the  iliac  crest,  and  it  is  inserted  by  a  single 
tendon.     The  two  parts  of  the  triceps  abductor  fern  oris  are  closely  blended,  and 


268  COMPARATIVE    MYOLOGY. 

the  auterior  one  has  no  ischial  origin.  The  sartor i  us  has  an  origin  from  the 
venter  of  the  ilium,  and  its  fleshy  portion  reaches  the  tihia.  The  gracilis  i* 
very  small  and  thin. 

In  the  anterior  tibial  region  we  find  the  following  muscles  : — The  tibialis 
aniicus,  corresponding  to  the  fleshy  portion  of  the  flexor  metatarsi,  partly 
covers  the  extensor  communis  ;  it  arises  from  tTie  tibial  crest  and  tuberosity,, 
receives  a  slip  from  the  peroneus,  and  is  inserted  by  a  tendon  to  the  meta- 
tarsal element  of  the  hallux.  If  the  hallux  is  complete,  a  tendinous  slip 
passes  to  the  distal  phalanx.  The  tendon  of  this  muscle  is  bound  down  by  a 
fibrous  band,  from  which  a  strong  slip  passes  imder  the  tendon,  becoming 
attached  to  the  tibia,  and  to  the  metatarsal  bone  of  the  middle  digit,  to  some 
extent  corresponding  to  the  fibrous  portion  of  the  flexor  metatarsi.  The 
extensor  communis  digitorum  arises  by  a  strong  tendon  from  between  the 
femoral  condyle  and  the  trochlea  ;  its  tendon  of  insertion  passes  over  the  tarsus 
much  in  the  usual  manner,  divides  into  four  slips,  and  is  inserted  as  in  the 
anterior  limb.  The  ijeroneus  longus  is  placed  between  the  preceding  muscle 
and  the  peroneus  brevis  ;  it  arises  from  the  superior  part  of  the  tibia,  and 
its  tendon,  reaching  the  tarsus,  divides,  a  slip  passing  inwards  to  the  first  meta- 
tarsal bone,  the  rest  winding  roimd  the  cuboid  to  gain  the  back  of  the  joint, 
and  become  attached  to  the  metatarsal  bone  of  the  hallux.  This  muscle  seema 
to  be  an  abductor  of  the  extremity.  The  peroneus  brevis  consists  of  two  parts. 
— a  superior,  arising  from  the  upper  third  of  the  fibula,  and  having  a  long  thui 
tendon,  which  passes  underneath  the  peroneus  longus,  descends  and  joins  the 
extensor  tendon  of  the  external  digit.  The  inferior  part  is  permiform,  and 
arises  also  from  the  fibula,  ending  in  a  strong  tendon  which  is  inserted  to  the 
external  metatarsal  bone.  The  superior  portion  is  the  extensor  proprius  of  the 
outer  digit,  the  inferior  an  abductor  of  the  extremity. 

In  the  posterior  tibial  region  we  find  the  plantaris  wanting.  The  flexor 
perforatus  is  somewhat  blended  with  the  gastrocnemius,  and  its  tendon 
is  divided  into  four  parts,  and  inserted  as  in  the  anterior  extremity. 
The  perforans  tendon  divides  into  four,  and  if  the  hallux  is  perfect  into  five 
slips,  proceeding  to  the  distal  phalanges.  Between  the  perforans  and  flexor 
accessorius  is  a  separate  muscle,  the  tibialis  posticus,  very  tliin  and  slender, 
arising  from  the  fibula  and  tibia  above,  its  tendon  accompanying  that  of  the 
accessorius  into  its  sheath,  and  afterwards  becoming  blended  with  the  posterior 
tai'sal  ligament. 

We  note  the  following  muscles  in  the  metatarsal  region.  The  extensor  pedis 
brevis  consists  usuallj^  of  three  bundles,  and  it  joins  the  extensor  tendons  of  the 
three  outer  digits.  The  perferans  has  a  small  accessory  muscle,  which  arises  on 
the  outside  of  the  tarsus.  The  lumbricales  and  interossei  resemble  their  ana- 
logues of  the  metacarpus.  The  muscles  proper  to  the  hallux  are  either  absent, 
or  too  rudimentary  to  merit  notice.  An  abductor  minimi  digiti  is  present^ 
and  corresponds  to  that  of  the  metacarpus. 

RODENTIA. 
The  most  prominent  feature  in  the  myology  of  the  rabbit  is  the  enormoua 
development  of  the  dorso-lumbar,  sublumbar,  gluteal,  and  femoral  muscles. 


RODENTIA AVES.  269 

The  longissimus  dor  si  is  attached  to  the  maramillary  processes  of  the  lumbar 
vertebrae.  The  muscles  of  mastication  are  also  well  developed,  especially  the 
masseter. 

The  muscles  of  the  limbs  bear  a  general  resemblance  to  those  of  the  dog. 
In  the  fore-arm  there  is  no  rotation,  hence  we  find  the  supinator  longus  and 
pronator  quadratus  wanting ;  the  other  rotators  being  small,  and  acting  as 
mere  flexors  of  the  elbow  joint. 

AVES. 

A  remarkable  feature  in  the  muscular  system  of  birds  is  the  liability  of  the 
tendons  to  ossification,  and  this  condition  is  by  no  means  peculiar  to  old 
animals. 

Comparing,  in  the  wide  sense,  the  muscles  of  a  bird  with  those  of  a  mammal, 
we  are  struck  with  their  wonderful  morphological  siijailarity,  although  the 
peculiarities  of  the  skeleton,  and  physiological  characteristics  of  the  animal 
lead  to  various  deviations  in  their  form  and  development. 

The  muscles  of  the  pectoral  limbs,  and  notably  those  of  the  pectoral  group, 
are  the  muscles  of  flight.  There  are  two  pectoral  muscles,  which  may  be 
called  the  magnus  and  parvus.  The  magnus,  an  enormous  muscle,  is  the 
depressor  of  the  wing  (depressor  alae)  ;  it  is  placed  posteriorly,  arising  from 
the  whole  of  the  sternum,  carina,  and  last  ribs,  and  being  inserted  to  the 
humerus  near  its  head.  The  pectoralis  parvus  (levator  alse)  is  small,  and 
situated  in  the  depression  between  the  clavicle  and  coracoid  bone,  its  tendon 
of  insertion  passing  inside  and  over  the  neck  of  the  scapula^  as  over  a  pulley, 
and  becoming  inserted  to  the  humerus  ;  this  is  the  levator  of  the  wing. 

A  peculiar  arrangement  of  the  muscles  enables  the  perching  birds  to  "roost." 
A  kind  of  ligament  passes  over  the  front  of  the  knee  joint  and  joins  the  flexor 
tendon,  so  that  when  the  tibia  is  flexed  on  the  femur,  the  digits  are  also  flexedj 
Hence  during  sleep,  when  the  weight  of  the  animal  flexes  the  knee-joint, 
simultaneously  it  causes  the  digits  to  clasp  the  perch. 

The  diaphragm  in  birds  is  said  to  assist  both  in.  the  dilatation  of  the  lungs, 
and  of  the  air  sacs.  Some  authorities,  however,  dispute  ita  existence,  othera 
again  describe  it  as  rudimentary. 


CHAPTER  IV. 
SPLANCHNOLOGY. 


This  section  of  the  subject  treats  of  the  viscera,  or  organs  which 
occupy  chiefly  the  cavities  of  the  body,  and  compose  respectively 
the  digestive,  respiratory,  urinary,  and  genital  systems,  all  of 
which  communicate  with  the  outside  world  by  apertures  on  the 
surface  of  the  body.  We  will  describe  these  systems  in  the  order 
here  given,  first  noting  that  in  all  of  them  there  is  a  certain 
similarity  in  structure,  in  so  far  that  each  consists  of  a  tube  oi 
canal,  lined  by  mucous  membrane,  and  provided  with  various 
glands  and  other  accessory  organs. 

Before  treating  of  these  systems,  it  will  be  advisable  to  alludt 
briefly  to  certain  tissues  and  structures  which  are  closely  associ- 
ated with  them.  These  are  epithelium,  mucous  and  serous 
membranes,  and  glands.  Involuntary  muscular  tissue  which 
occurs  extensively  in  these  organs  has  been  alluded  to  already. 
(See  p.  157.) 

EPITHELIUM. 
This  is  a  tissue  cousistiug  chiefly  of  cells,  which,  in  one  form 
or  other,  covers  all  the  free  surfaces  of 
the  body — i.  e.,  the  skin  and  mucous 
membranes  ;  one  variety  of  it  also  covers 
the  inner  surfaces  of  closed  and  air-tight 
membranous  sacs,  the  serous  and  syno- 
vial membranes,  in  which  case  it  is  dis- 
tinctively known  as  endotkelium.  The 
following  varieties  of  epithelium  are  de- 
scribed : —  squamous,  columnar,  sphe- 
roidal, and  ciliated. 

Squamous,     tesselated,    pavemental,    or 

scaly   epithelium    consists   of    flattened    scaly    cells,    usually 

arranged  in  superimposed  layers.     In  shape  irregularly  oval, 

these  cells  vary  somewhat,  those  on  the  surface  being  more 

270 


Fio.  88: 

Detached  epithelium  cells 
from  the  mucous  membrane 
of  the  mouth,  a.  Cell  wall ; 
h.  Nucleus  ;  c,  Nucleolus. 


EPITHELIUM. 


271 


fattened  tlian  tliose  of  the  deeper  layers,  which  are  more  spher- 
ical in  form.  They  contain  protoplasm,  a  nucleus,  and  a  number 
of  granules.  The  superficial  cells  are  evontually  cast  off,  the 
deeper  ones  taking  their  place,  and  the  latter  become  more  and 
more  flattened  as  they  approach  the  surface.  Consisting  thus  of 
layers  or  strata  of  cells,  the  name  stratified  epithelium  has  been 
applied  to  this  tissue;  it  is  found  in  the  alimentary  mucous 
membrane,  from  tLe  mouth  to  the  first  half  of  the  stomach,  in 
the  bladder,  the  rectum,  the  entrances  to  the  nose,  the  eye, 
urethra,  and  vagina,  and  in  a  dried  and  desquamating  form  it 
constitutes  the  epidermis  or  scarf  skin  ;  it  is  non- vascular,  and 
for  the  most  part  non-sensitive. 

Endothelium. — This  resembles  epithelium  in  structure,  differ- 
ing in  its  situation,  as  above  described,  and  in  the  fact  that  it  is 
arranged  as  a  single  layer  of  flattened  cells. 

Columnar  or  cylindrical  epithelium. — In  this  variety  the  cells 
are  cylindrical  in  form,  and  arranged  side  by  side,  with  their  long 
axes  perpendicular  to  the  subjacent  surface.  Their  contents 
resemble  those  of  the  squamous  kind,  but  the  nucleus  is  more 
distinct.  This  form  of  epithelium  is  found  on  the  mucous 
membrane  of  the  intestines  and  pyloric  half  of  the  stomach,  and 
it  is  continued  into  the  ducts  of  the  glands  which  open  on  the 
surface  of  the  membrane.  The  cells  covering  the  villi  of  the 
intestine  have  expanded  free  extremities,  which  may  appear 
slightly  striped. 

Spheroidal  or  Polyhedral  epithelium  is  found  in  the  follicles 
and  ducts  of  glands,  hence  the  name  glandular  epithelium.  The 
cells  of  this  variety  are  spheroidal,  or  it  may  be  irregularly 
polyhedral  in  shape.  A  variety  known  as  transitorial  occurs  in 
ihe  mucous  membrane  of  the 
urinary  bladder,  the  cells  being 
transitional  in  form  between 
those  of  columnar  and  scaly 
iinds,  and  arranged  in  a  small 
number  of  layers. 

Ciliated  epithelium  consists 
of  columnar  cells,  provided  at 
their  free  extremities  with  delicate  hair-like  processes  or  cilia, 
which  wave  to  and  fro  in  a  marked  manner.  The  motion  is 
apparently  independent  of  the  direct  influence  of  the  nervous 
system,  since  it  is  observable  for  some  time  after  the  death  of 


ciliated  epithelium,   highly  magnified. 
a,  Nucleated  cells ;  6.  Cilia. 


272  SPLANCHNOLOGY. 

the  animal.  This  tissue  is  found  in  the  mucous  membrane^ 
of  the  air-passages,  where  its  cilia  tend  by  their  motion  to  expel 
particles  of  foreign  matter  which  are  inhaled  with  the  breath ; 
it  is  found  also  in  the  ventricles  of  the  brain,  in  the  canal  of  the 
spinal  cord,  and  in  the  mucous  membrane  lining  the  uterus 
and  Fallopian  tubes  of  the  female,  and  part  of  that  lining  the 
vas  deferens  of  the  male  ;  and  in  the  convoluted  uriniferous 
tubes. 


MUCOUS    MEMBRANES. 

These  structures  are  widely  diffused,  lining  the  canals  of  the 
four  systems  now  under  consideration,  and  becoming  continuous 
with  the  skin  at  each  of  their  orifices.  A  mucous  membrane  con- 
sists of  one  or  more  layers  of  epithelial  cells  placed  upon  a  sub- 
epithelial layer  or  corium,  the  latter  consisting  of  a  modified 
form  of  connective  tissue,  and  serving  as  a  matrix  in  which  are 
situated  the  nerves  and  vessels  of  the  membrane,  together  with 
numerous  glands. 

Some  authorities  have  described  a  membrane  separating  the 
cellular  from  the  vascular  layer,  and  it  has  received  the  name  of 
the  basement  membrane.  By  others  it  is  regarded  as  a  mere 
condensation  of  the  corium.  The  secretion  of  the  glands  proper 
to  the  mucous  membranes  is  mucus,  a  viscid  fluid  which  lubri- 
cates their  free  surfaces.  The  surface  of  a  mucous  membrane 
may  be  smooth,  as  in  the  air-passages,  or  it  may  be  papillated — 
i.e.,  furnished  with  small  projections,  papillae,  as  in  the  tongue  ; 
it  may  be  rugeous,  or  thrown  into  folds  or  rugas,  as  in  the  oeso- 
phagus and  stomach  ;  in  the  small  intestine  it  presents  finger-like 
projections  termed  villi,  and  is  then  said  to  be  villous,  and  in  the 
same  situation  the  membrane  presents  valve-like  folds,  and  may 
be  termed  valvular. 

The  mucous  membrane  which  lines  the  digestive  canal  becomes 
continuous  in  the  pharynx  Avith  that  lining  the  respiratory  canal, 
the  pharynx  being  a  cavity  common  to  the  two  systems  ;  hence 
the  entire  membrane  may  be  termed  the  gastro-pulmonaoy 
mucous  membrane,  which  is  also  produced  so  as  to  line  the 
Eustachian  tube  and  tympanic  cavity  of  the  ear,  and  is,  in  some 
animals,  continuous  by  means  of  the  lachrymal  duct  with  the 
conjunctiva  of  the  eye.  At  the  lips  and  anus  it  is  directly  con- 
tinuous with  the  skin.  In  a  similar  manner,  the  mucous  mem- 
brane of  the  urinary  canal  becomes  continuous  with  that  of  the 


SEROUS    MEMBRANES.  273 

genital  eanal  in  the  vagina  in  the  female,  in  the  urethra  in  the 
male;  the  membrane  so  formed  is  termed  the  urino-genital 
mucous  membrane,  and  it  becomes  continuous  with  the  skin  at 
the  orifices  of  these  organs.  Mucous  membrane  also  lines  the 
ducts  of  the  mammary  glands;  and  in  fact  the  ducts  of  all 
glands  which  open  on  the  skin  or  mucous  membranes. 

SEROUS    MEMBRANES. 

The  closed  cavities  of  the  body  are  lined  by  membranous 
structures  of  this  class.  By  a  closed  cavity  we  understand  a 
receptacle  impervious,  under  normal  circumstances,  to  the  atmo- 
spheric air.  A  serous  membrane  consists  of  an  endothelial  and  a 
subendothelial  portion,  the  cells  of  the  former  being  arranged  in 
a  single  layer.  Synovial  membranes  may-be  regarded  as  a  variety 
of  serous  membranes,  differing  chiefly  in  the  nature  of  their  secre- 
tion ;  they  have  already  been  described  (see  p  125).  Since  a 
serous  raembrane  is  so  arranged  as  to  line  a  closed  cavity,  and  at 
the  same  time  to  cover  its  contents,  it  follows  that  the  entire 
membrane  must  form  a  closed  sac,  the  endothelial  layer  being  on 
the  inside ;  such  a  sac  is  called  a  serous  sac  or  cavity.  The  fold 
of  the  membrane  which  lines  a  cavity  is  called  the  parietal,  that 
which  covers  its  contents  the  visceral  portion ;  the  two  surfacea 
contacting,  and  gliding  readily  upon  each  other,  are  lubricated  hy 
a  fluid  secretion  contained  in  the  sac ;  hence  one  use  of  these 
membranes  is  to  prevent  friction  between  the  walls  of  cavities 
and  the  organs  contained  therein.  The  following  are  the  serous 
membranes  and  their  position  in  the  body : — The  arachnoid 
membranes  form  closed  sacs,  situated,  one  between  the  two 
cbverings  of  the  brain,  the  other  between  those  of  the  spinal 
cord.  The  peritoneum  lines  the  abdominal  cavity  and  covers  its 
viscera;  the  pleurae,  right  and  left,  each  covers  the  lung,  and 
lines  the  half  of  the  thoracic  cavity  of  its  own  side.  The  peri- 
cardium lines  the  fibrous  sac  which  contains  and  supports  the 
heart,  and  also  covers  the  latter.  The  cavities  of  the  heart  are 
also  lined  by  a  membrane  of  a  serous  nature — the  endocardium 
— which  is  continued  through  the  veins  and  arteries;  as  the 
chief  lymphatic  vessels  communicate  with  the  venous  system,  the 
endothelial  lining  of  the  former  becomes  continuous  with  that  of 
the  latter.  Lymphatic  vessels  open  into  the  serous  sacs  by  very 
small  apertures,  or  stomata,  so  that  these  sacs  are  now  con- 

T 


274  SPLANCHNOLOGY. 

sidered  as  being  depositories  of  lymph ;  and  "  thus  a  continuity 
of  surface  is  established  between  the  serous  membranes  and  the 
lining  membrane  of  the  blood-vascular  system  through  the 
lymphatics  "  {Turner). 

GLANDS. 

Without  attempting  an  exhaustive  definition  of  the  glands,  it 
may  suffice  to  state  here  that  for  the  most  part  they  are  organs 
in  which  is  carried  on  the  process  of  secretion,  or  separation  from 
the  blood  of  certain  matters,  which  may  be  required  to  assist  in 
the  various  vital  functions,  or  may  be  destined  to  be  speedily  cast 
off  as  effete  or  poisonous  material.  Most  glands  in  their  typical 
structure  resemble  a  mucous  membrane,  consisting  of  epithelial, 
subepithelial,  vascular,  and  nervous  portions  ;  the  first  of  these 
portions  usually  rests  upon  a  condensed  layer  of  the  second, 
which  is  known  as  the  Tnembrana  propria,  or  basement  mem- 
brane. The  vessels  supply  the  gland  with  blood,  from  which 
the  secretion  peculiar  to  the  gland  is  separated  by  the  vital 
power  of  the  cells,  which  power  is  stimulated  by  the  nerves,  the 
latter  also  regulating  the  blood  supply.  Lymphatic  vessels  are 
present,  but  their  use  in  these  organs  is  obscure.  The  sub- 
epithelial  tissue  supports  the  other  component  structures  of  the 
gland,  at  the  same  time  determining  its  anatomical  form.  The 
secretions  of  glands  are,  as  a  rule,  discharged  on  the  free  surfaces 
of  the  body — i.e.,  on  the  mucous  membranes  or  skin — by  means 
of  tubes  known  as  the  gland-ducts  ;  hence  such  glands  may  be 
conveniently  regarded  as  depressions  in  the  mucous  membrane  or 
in  the  skin. 

When  a  gland  appears  as  a  tube-like  depression  in  the  mucous 
membrane  it  is  termed  a  follicle,  crypt,  or  simple  tubular 
gland ;  if  the  cavity  is  dilated,  it  is  known  as  a  sac,  or  saccular 
follicle ;  and  if  either  of  these  forms  be  provided  with  secondary 
recesses,  it  is  said  to  be  multilocular.  A  tubular  gland  may  be 
coiled  upon  itself;  or  it  may  branch,  in  which  case  it  becomes 
a  compound  tubular  gland.  A  tubular  depression  ending  in  a 
number  of  vesicular  recesses  constitutes  a  simple  racemose 
gland ;  a  compound  racemose  or  conglomerate  gland  consists  of 
a  number  of  simple  ones  with  a  common  duct. 

The  ductless  glands  form  a  group  which  difiers  from  any  of 
the  above  in  the  absence  of  a  duct,  the  secretion  usually  being 


EXPLANATION  OF  PLATE  IV. 


Digestive  Apparatus  of  the  Horse, 


1.  Mouth. 

11.  Small  intestine. 

2,  Pharynx. 

12.  Floating  colon. 

3.  (Esophagus. 

13.  Eectum. 

4.  Diaphragm. 

14.  Anus. 

5.  Spleen. 

15.  Left  kidney  atid  ureter. 

6.  Stomach  (left  sac). 

16.  Bladder. 

7.  Duodenum. 

17.  Urethra. 

8.  Liver  (upper  extremity). 

A.  Hard  palate. 

9.  Great  colon. 

B.  Tongue. 

tO.  Caecum. 

C.  Soft  palate. 

D.  Trachea. 

E.  Pulmonary 

artery  (divided). 

F.  Heart. 

G.  Posterior  ac 

rta. 

THE    ALIMENTARY    CANAL.  275 

-carried  away  by  rapture  of  the  glandular  sac,  or  by  absorption 
into  the  neighbouring  lymphatics. 

The  liver  has  been  termed  a  reticular  gland,  because  its  ducts 
form  a  network  at  their  origin. 


Digestive  System. 

The"  digestive  organs  comprise  the  alimentary  canal  and  its 
accessories,  by  which  the  alimentary  matter  is  received  and  sub- 
jected to  specific  actions,  which  adapt  it  for  purposes  of  nutri- 
tion. Digestion  therefore  embraces  the  collective  operations  and 
changes  which  the  food  undergoes  in  the  alimentary  canal. 

The  functional  processes  of  digestion  are — Prehension,  the 
taking  up  of  food,  which  is  performed  in  the  horse  by  the  lips  ; 
Mastication,  chewing,  grinding  ;  and,  simultaneously  with  this, 
Insalivation,  or  mixing  the  ingesta  with  the  fluid  secretion  of  the 
salivary  glands ;  Deglutition,  or  swallowing  the  prepared  food 
by  means  of  the  tongue,  pharynx,  and  oesophagus ;  Ghymifica- 
tion,  or  conversion  of  food  in  the  stomach  into  a  pultaceous 
chyme,  by  maceration  and  the  action  of  the  gastric  juice ; 
Chylification,  or  conversion  of  the  chyme  into  chyle,  a  change 
which  takes  place  in  the  duodenum,  presumably  "by  the  agency 
of  the  biliary  and  pancreatic  secretions;  Absorption  of  the 
nutrient  material  into  the  circulation  ;  and  finally,  Defecation  or 
excretion,  the  expulsion  of  residual  inert  matter. 


THE    ALIMENTARY    CANAL. 

The  alimentary  canal  is  a  musculo-membranous  tube  extend- 
ing from  the  lips  to  the  anus ;  its  walls  are  composed  of  muscular 
tissue,  for  the  most  part  of  the  non-striated  kind,  and  lined 
throughout  by  mucous  membrane.  It  consists  of  a  continuous 
series  of  tubes  and  cavities,  the  chief  of  which -are  the  Mouth, 
Pharynx,  CEsophagus,  Stomach,  and  the  Intestines.  It  may  be 
divided  into  three  portions — the  preparatory,  or  ingestive, 
embracing  the  mouth,  pharynx,  and  oesophagus,  in  which  the 
food  is  prepared ;  the  essential,  or  digestive,  including  the 
stomach  and  most  of  the  intestines,  where  the  food  passes 
through  various  changes,  and  is  deprived  of  its  nutritive  por- 
tions; and  the  egestive,  or  expulsive  portion,  by  which  the 
residue  is  expelled  from  the  system.      Each  division  is  provided 


276  SPLANCHNOLOGY. 

with  accessories,  the  preparatory  with   teeth  and  salivary  glands^ 
and  the  essential  organs  with  the  liver,  pancreas,  spleen,  &c. 

We  will  describe  the  parts  of  the  alimentary  canal  in  the  order 
above  given — the  order  in  which  the  food  traverses  them. 

THE    MOUTH. 

The  mouth  is  an  irregularly  oval  cavity  at  the  commencement 
of  the  alimentary  canal,  containing  the  organs  of  taste  and  the 
instruments  of  mastication  ;  it  is  situated  between  the  jaws,  its 
long  diameter  following  that  of  the  head.  It  is  pierced  by  two 
openings  ;  the  anterior  for  the  introduction  of  food,  and  the 
posterior,  through  which  the  latter  passes  into  the  pharynx.  It 
is  bounded  in  front  by  the  lips  and  their  aperture,  the  fissura 
oris,  and  laterally  by  the  cheeks  ;  the  roof  is  formed  by  the  hard 
palate  ;  its  floor  is  occupied  by  the  tongue,  while  the  posterior 
boundary  is  the  veluTYi  pendulum  palati,  or  soft  palate,  a  mem- 
branous partition  separating  it  from  the  pharynx.  The  mucous 
membrane  is  pale,  roseate,  continuous  with  the  skin  at  the  lips, 
and  covering  the  whole  free  surface  of  the  mouth  and  its  contents, 
excepting  the  teeth. 

THE    LIPS. 

The  labia,  or  lips,  superior  and  inferior,  are  movable  fleshjr 
curtains  surrounding  the  anterior  opening,  and  united  laterally  by 
a  commissure.  They  consist  of  skin  and  mucous  membrane, 
Avhich  enclose  muscles,  vessels,  nerves,  areolar  tissue,  fat,  and 
certain  labial  glands  situated  between  the  mucous  membrane  and 
muscle.  The  mucous  surface  of  each  lip  is  bridled  mesially  to 
the  gum  by  a  doubling  of  the  membrane,  constituting  the 
fra^num  labii  superioris  and  inferioris.  The  arterie-^,  and  veins 
of  the  lips  are  the  palato-labials  and  the  superior  and  inferior 
coronaries.  The  nerves  come  from  the  fifth  and  seventh  cranial 
pair,  the  first  supplying  the  sensory,  or  nerves  of  feeling,  which 
are  well  developed  in  the  lips  of  the  horse,  since  these  are  organs 
of  touch  as  well  as  of  prehension. 


THE    CHEEKS. 

The    buccal,   or  cheeks,   are    two  musculo-membranous   walls, 
-which  close  the  mouth  laterally  ;  they  are  continuous  with  the 


THE    SOFT    PALATE. 


277 


lips,  and  consist  of  an  external  cuticular,  a  central  muscular,  and 
an  internal  mucous  coat  ;  the  latter  is  termed  the  buccal  mem- 
brane, and .  is  provided  with  numerous  small  buccal  glands, 
similar  to  the  labial  ones,  which  open  on  its  surface  by  straight 
projecting  pointlets  ;  a  few  larger  ones  are  known  as  the  molar 
glands.  On  the  buccal  membrane  of  each  side,  near  the  third 
upper  molar  tooth,  is  a  papilla,  in  which  is  the  opening  of  the 
duct  of  the  parotid  gland.  The  gingivce,  or  gums,  are  reflections 
of  the  buccal  membrane,  and  contain  dense  fibrous  tissue,  con- 
tinuous with  the  periosteum  of  the  alveolar  processes,  with  an 
epithelial  covering ;  they  embrace,  without  being  attached  to, 
the  necks  of  the  teeth,  and  are  reflected  into  the  alveoli.  The 
chief  arteries  and  veins  of  the  cheek  are  the  facial  and  the 
coronaries.  The  nerves  come  from  the  same  source  as  those  of 
the  lips.  The  cheeks  by  their  muscles  serve  during  mastication 
to  support  the  food,  and  press  it  between  the  molars. 

THE    HARD    PALATE. 

The  hard  palate,  or  mouth-roof,  is  Ibounded  anteriorly  by  the 
incisor  teeth,  posteriorly  by  the  soft  palate.  It  is  firmly  attached 
to  the  bony  palate,  formed  by  the  palatine  bones  and  palatine 
processes  of  the  superior  and  premaxillse.  It  consists  of  a  dense 
layer  of  mucous  membrane,  with  a  thick  subjacent  layer  of 
fibrous  tissue.  It  is  equally  divided  by  a  longitudinal  groove 
corresponding  to  the  palatine  suture,  which  originates  anteriorly 
at  the  base  of  a  small  tubercle.  From  this  raphe  spring  trans- 
verse ridges,  which  divide  the  palate  into  a  number  of  arches 
with  their  concavities  backwards  ;  they  become  smaller  posteri- 
orly, and  are  from  seventeen  to  twenty  in  number. 

The  palate  is  supplied  with  blood  from  the  palatine  arteries, 
returned  in  a  venous  plexus,  which  forms  a  kind  of  erectile  tissue 
in  the  submucous  layer.  The  sensory  nerves  come  from  the 
superior  maxillary  division  of  the  fifth  pair.  The  hard  palate 
furnishes  a  fixed  surface,  against  which  the  tongue  can  mani- 
pulate the  food. 

THE    SOFT    PALATE. 

The  soft  palate,  or  velum  pendulum  palati,  is  the  valvular 
curtain  suspended  between  the  mouth  and  the  pharynx,  and  it 
consists  of  a  double  fold  of  mucous  membrane,  enclosing  muscles, 
glands,  vessels,  and  nerves.     It  presents  two  surfaces  and  four 


278  SPLANCHNOLOGY. 

borders.  Its  superior  border  is  attached  to  the  palatine  arch, 
and  is  continuous  with  the  hard  palate,  whence  the  velum  passes 
downwards  and  backwards.  The  lateral  borders  are  united  to 
the  line  of  demarcation  between  the  cavity  of  the  mouth  and  that 
of  the  pharynx.  The  inferior  border  is  concave  and  free,  resting 
upon,  and  closely  embracing  the  base  of  the  epiglottis.  From 
the  extremities  of  this  border,  two  very  thin  prolongations  run 
along  the  lateral  walls  of  the  pharynx  as  far  as  the  beginning  of 
the  oesophagus;  these  are  the  'posterior  pillars  of  the  fauces. 
Between  the  free  border  of  the  velum  pendulum  palati  and  base 
of  the  epiglottis  is  the  posterior  opening  of  the  mouth,  called  the 
isthmus  faucium,  which  in  the  horse,  from  the  extreme  development 
of  the  soft  palate,  is  constantly  shut,  except  during  the  passage  of 
food  or  water.  It  is  owing  to  the  great  size  of  the  velum  that  a 
horse  is  unable  to  breathe  through  his  mouth.  The  anterior 
surface  of  the  velum  forms  the  posterior  boundary  of  the  mouth, 
is  marked  by  longitudinal  folds  and  transverse  lines,  and  studded 
with  the  mouthlets  of  numerous  submucous  glands.  This  surface 
is  united  laterally  to  the  base  of  the  tongue  by  large  mucous 
columns,  the  posterior  pillars  of  the  tongue,  or  anterior  pillars 
of  the  fauces.  Behind  these  are  two  lateral  triangular  spaces,  the 
tonsilar  spaces,  which  take  the  place  of  the  tonsils  or  amygdalce, 
these  being  absent  in  the  horse;  numerous  gland  ducts  open  in 
these  spaces.  The  posterior  surface  of  the  soft  palate  is  convex, 
and  forms  the  anterior  wall  of  the  pharynx ;  it  presents  three 
very  small  longitudinal  ridges. 

MUSCLES    OF    THE    SOFT    PALATE. 
A  strong  layer  of  aponeurosis  or  fibrous  tissue,  the  staphyline 
aponeurosis,  forms  as  it  were  the  foundation  of  the  soft  palate, 
being  attached  above  to  the  palatine  arch.    The  following  muscles 
control  the  soft  palate  : — 

Teusor  palati.  I  Pharyngo-staphylinus. 

Levator  palati.  |  Palato-staphylinus. 

Palato-glossus. 

TENSOR    PALATL 

{Peristaphylinus  Externus.) 

(Fig.  90.  i.) 

A   long  slender  muscle  with    tendinous  extremities,  running 
longitudinally  between  the  levator  palati  and  the  pterygoidei.     It 


MUSCLES  OF  THE  SOFT  PALATE. 


279 


arises  from  the  petrosal  styloid  process  ;  its  tendon  of  insertion, 
playing  over  the  staphyline  groove,  expands  and  becomes  lost 
in  the  fibrous  layer  of  the  velum,  of  which  it  is  a  tensor  and 
depressor. 

LEVATOR    PALATl. 

( Peristaphijlinus  Internus. ) 

(Pig.  90.  h.) 

A  slender  muscle  which  arises  with  the  last-named  one,  and 
lies  between  it  and  the  Eustachian  tube.  It  passes  directly  to 
the  soft  palate  expanding  between  the  Pharyngo-staphylinus  and 
the  Palato-staphylinus,  and  finally  joins  its  fellow  of  the  opposite 
side.      It  raises  the  velum 


Fig   90. 

Right  infero-lateral  view  of  the  muscles  of  the  nia.\illary  space  ;  the  ramus  and  hyoid  cornu  are 
«nt  away,     a,  Lingualis  :  6  6,  Hyo-glossus  longus  ;  c,  Hyo-glossus  brevis ;  d,  Genio-hyo-glossus 
<,  Genio-hyoideus :  /,  Stylo-hyoideus  :  g,  Hyoideus  magnus;  7i.  Levator  palati ;  i.  Tensor  palati 
k,   Pharyngo-staphylinus :    I,  Pterygo-pharsmgeus  ;    m.  Kerato-pharyngeus ;  n,  Hyo-pharyngeus 
c,  Thyro-pharyngeus ;  p,  Crico-pharyngeus  :  q,  OEsophagus. 


PHARYNGO-STAPHYLINUS. 

{Staphylinus  Communis.) 

(Fig.  90.  i.) 

This  is  a  broad,  thin  muscle,  occupying  the  inferior  half  of  the 
velum,  and  meeting  its  fellow  in  the  median  line ;  they  are 
sometimes  described  as  a  single  muscle.  The  fibres  run  back- 
wards and  outwards,  and  a  portion,  after  following  the  free  border 
of  the  velum,  is  continued  under  the   pharyngeal  raucous  mem- 


280  SPLANCHNOLOGY. 

brane  and  attached  to  the  thyroid  cartilage ;  this  portion  helps 
to  form  the  posterior  pillar  of  its  own  side.  This  muscle  is 
chiefly  a  tensor  of  the  velum. 


PALATO-STAPHTLINUS. 

{Azygos  Uvulce — Human.) 

This  is  a  small  cylindrical  muscle  contacting  its  fellow  of  the 
opposite  side,  and  arising  by  a  small  tendon  from  the  palatine 
arch  and  staphyline  aponeurosis,  to  become  attached  to  the  free 
border  of  the  velum  at  its  middle  ;  the  pair  of  muscles  thus 
indicate  the  right  and  left  halves  of  the  structure.  The  action 
of  this  muscle  is  to  raise  and  draw  forwards  the  velum,  thus 
helping  to  dilate  the  isthmus. 

PALATO-GLOSSUS. 

If  this  muscle  exists  in  the  horse,  it  will  be  found  under  the 
mucus  membrane  of  the  anterior  pillar,  which  it  helps  to  form, 
thus  joining  the  soft  palate  and  the  tongue. 

The  soft  palate  is  supplied  with  blood  by  the  staphyline  and 
pharyngeal  arteries.  Its  nerves  come  from  the  second  division 
of  the  fifth  pair,  and  from  Meckel's  ganglion.  It  acts  as  a  valve 
between  the  niouth  and  pharynx,  opening  to  allow  the  passage  of 
alimentary  materials  during  deglutition,  but  completely  prevent- 
ing the  return  of  such  from  the  pharynx  to  the  mouth ;  hence  in 
case  of  vomition  in  the  horse  the  material  is  voided  through  the 
nasal  chambers.  Respiration  is  likewise  effected  in  the  solipede 
only  through  the  nose. 

\ 

THE  TONGUE. 

The  tongue  is  a  movable,  musculo-membranous  organ,  situated 
on  the  floor  of  the  mouth,  between  the  rami  of  the  lower  jaw  ; 
the  space  it  occupies  is  termed  the  lingual  canal.  It  is  the 
special  organ  of  iaste,  and  at  the  same  time  materially  assists  in 
mastication  and  deglutition.  In  the  ox  it  is  prehensile,  and  the 
carnivora  lap  or  prebend  water  with  it.  The  tongue  consists  of 
muscles,  glands,  vessels,  and  nerves,  having  its  free  surface 
enveloped   by  mucous  membrane,  which  varies  in  thickness, 


LINGUAL   MUSCLES.  281 

being  smootli  and  pellucid  infero-laterally,  where  tlie  ranine 
vein  can  be  traced.  Irrci^ularly  pyramidal  in  shape,  it  has  a 
root  or  base,  a  body,  and  an  apex  or  tip. 

The  base,  the  widest  and  thickest  part,  is  muscularly  attached 
to  the  OS  hyoides  and  inferior  maxilla;  to  the  epiglottis  by  a  fold 
of  mucous  membrane,  the  glosso-epiglottic  ligament ;  and  to  the 
velum  pendulum  palati  by  the  anterior  pillars  of  the  fauces. 
The  apecc,  or  tip,  is  free,  and  broa'd  in  the  horse,  being  directed 
forwards  against  the  inner  surfaces  of  the  lower  incisors.  The 
under  surface  of  the  tongue  is  attached  anteriorly  to  the  lower 
jaw  by  the  genio-hyo-glossi  muscles,  and  laterally  by  the  reflec- 
tion of  the  mucous  membrane,  over  the  sublingual  glands,  to 
the  inner  surface  of  the  inferior  gums.  Antero-mesially,  the 
mucous  membrane  folds  into  a  frcenura  linguae,  or  anterior 
pillar,  in  front  of  which  is  a  small  papilla,  containing  the 
openings  of  the  submaxillary  glands ;  and  on  either  side, 
between  the  tongue  and  maxilla,  are  the  ducts  of  the  sublingual 
glands. 

The  dorsum,  or  upper  surface,  is  convex,  and  marked  along 
its  middle  by  a  raphe,  or  groove,  which  indicates  the  division  of 
the  organ  into  two  lateral  halves.  The  raphe  terminates  near 
the  base  in  a  cavity  known  as  the  foramen  coicum,  or  foramen  of 
Morgagni,  in  which  numerous  mucous  follicles  open. 

Posteriorly  the  tongue  is  divided  by  fibrous  tissue,  which  forms 
a  partial  longitudinal  septem,  commencing  near  the  hyoid  bone, 
and  losing  itself  in  the  muscles.  According  to  Briihl,  a  piece  of 
fibro-cartilage  exists  here,  peculiar  to  the  solipede,  and  it  has 
been  named  the  lingual  cartilage. 


LINGUAL    MUSCLES. 

The  substance  of  the  tongue  is  composed  chiefly  of  muscular 
layers  running  in  different  directions,  between  which  adipose 
tissue  is  interposed.  The  muscles  are  divided  into  extrinsic  and 
intrinsic. 

The  extrinsic  muscles  of  the  tongue  are  as  follows  : — 

Hyo-glossus  longus.  Genio-hyo-glossus. 

Hyo-glossus  brevis.  Pharyngo-glossus. 

Hyo-glossus  parvus.  Palato-glossus. 


282  SPLANCHNOLOGY. 

HYO-GLOSSUS   LONGUS. 

(Stylo-glosstcs.) 
(Tig.  90,  6  h.) 

Situated  along  the  border  of  the  tongue,  this  muscle  is  long 
and  flat. 

Origin. — From  the  external  surface  of  the  comu  of  the  os 
hyoides. 

Insertion. — To  the  substance  of  the  tongue  expanding  towards 
the  tip. 

Relation. — Externally  with  the  mylo-hyoideus  and  sublingual 
gland,  sublingual  nerve,  and  canal  of  Wharton ;  internally  with 
the  genio-hyo-glossus  and  hyo-glossus  brevis. 

Action. — With  its  fellow,  to  retract  the  tongue  within  the 
mouth ;  singly,  to  draw  it  to  one  side. 

HTO-GLOSSUS   BREVIS. 

{Basio-glossus.) 

(Fig.  90.  c.) 

Situated  on  the  inner  surface  of  the  hyo-glossus  longus,  it  is 
a  broad,  flat,  and  somewhat  radiating  muscle,  the  fibres  passing 
obliquely  forwards  and  upwards. 

Origin. — From  the  side  of  the  body  and  spur  process  of  the  os 
hyoides  and  the  inferior  part  of  the  comu. 

Insertion. — The  side  of  the  tongue,  passing  inwards  to  form 
the  "  transverse  fibres." 

Relation. — Externally  with  the  mylo-hyoideus  and  hyo-glossus 
longus,  the  hypoglossal  nerve,  Wharton's  canal,  and  the  mucous 
membrane  of  the  tongue  ;  internally  with  the  hyoideus  parvus  and 
the  corniculum,  genio-hyo-glossus,  the  lingual  artery,  and  the 
glosso-pharyngeal  nerve. 

Action. — To  draw  the  base  of  the  tongue  downwards  and  back- 
wards, on  one  side,  or  both  if  acting  with  its  fellow. 

HYO-GLOSSUS   PARVUS. 

Situated  immediately  under  the  mucous  membrane,^intimately 
blended  with  the  last  named,  this  is  a  small  radiating  muscle. 

Attachments. — It  arises  from  the  inner  aspect  of  the  corniculum 
and  hyoid  bone,  crosses  the  hyoideus  transversus,  its  fibres  then 
running  forwards.  It  expands  over  the  dorsum  and  sides  of  the 
tongue,  its  fibres  crossing  those  of  the  hyo-glossus  brevis. 


LINGUAL    MUSCLES.  283 

GENIO-HYO-GLOSSUS 

(Genio-glossus.) 
(Fig.  90.  d.) 

Situated  in  the  vertical  median  plane  of  the  tongue,  this  is  a 
broad,  thin,  and  fan-shaped  muscle,  its  fibres  radiating  upwards. 

Attachments. — Its  basis  may  be  said  to  stretch  from  the  hyoid 
bone  to  near  the  maxillary  symphysis,  the  radiating  fibres  passing 
upwards  and  some  backwards,  some  forwards,  buried  in  the  sub- 
stance of  the  tongue. 

Relation. — Internally  with  its  fellow ;  inferiorly  with  the  genio- 
hyoideus ;  externally  with  the  hyo-glossus  longus  and  brevis,  the 
sublingual  gland,  and  the  lingual  artery.  The  anterior  borders 
of  this  pair  of  muscles  help  to  form  the  frsenum  lingnse.  Poste- 
riorly a  certain  amount  of  fat  constantly  occurs  between  them. 

Action. — This  varies.  It  may  protrude  the  tongue  by  depress- 
ing the  dorsum,  or  help  to  retract  it ;  or  it  may  depress  the  entire 
organ,  according  to  the  part  of  the  muscle  which  acts,  and  to 
co-operation  of  the  other  muscles, 

PHARYNGO-GLOSSUS. 

This  name  has  been  applied  to  a  few  fibres  which  unite  the 
tongue  to  the  lateral  wall  of  the  pharynx,  passing  between  the 
fibres  of  the  genio-hyo-glossus  and  hyo-glossus  parvus,  and  blend- 
ing with  them, 

PALATO-GLOSSUS. 

(See  muscles  of  the  soft  palate.) 

The  intrinsic  muscles  are  collectively  described  under  the 
name 

LINGUALIS. 
(Fig.  90.  a.) 

This  muscle  is  arranged  in  two  layers  of  locgitudinal,  with  an 
intervening  set  of  transverse,  fibres.  The  lingualis  superficialis 
lies  on  the  upper  surface  of  the  tongue  just  below  the  mucous 
membrane,  running  longitudinally  from  the  apex  nearly  to  the 
OS  hyoides.      The  lingualis  inferior,  also  longitudinal  in  direc- 


284  SPLANCHNOLOGY. 

tion,  is  arranged  in  a  rounded  band,  which  extends  in  the  inferior 
region  of  the  tongue  from  base  to  apex,  a  few  fibres  reaching  the 
hyoid  bone.  The  lingualis  transversus  lies  between  the  super- 
ficial and  deep  layers,  intersecting  the  extrinsic  muscles ;  its  fibres 
are  always  intermixed  with  a  quantity  of  adipose  tissue,  and  form 
the  bulk  of  the  organ.  These  layers  alter  the  form  of  the  tongue, 
the  superficial  tilting  the  tip  upwards ;  the  inferior  curves  it  down- 
wards; while  the  transverse  protracts  or  elongates  it. 

The  fibres  of  the  intrinsic  muscles  are  regarded  by  Chauveau 
and  others  as  prolongations  of  the'  extrinsic  muscular  fibres. 

The  mucous  membrane  is  plentifully  supplied  with  glands, 
simple  and  compound.  The  simple  are  mere  follicles,  secreting 
mucus.  The  compound  glands,  and  certain  closed  follicles,  are 
found  chiefly  at  the  base  of  the  tongue,  about  the  foramen  csecum, 
posterior  pillars,  and  papillae  circumvallatse,  into  which  many  of 
their  ducts  open. 

LINGUAL   PAPILLiE. 

The  mucous  membrane  covering  the  under  part  of  the  free 
surface  of  the  tongue  is  smooth,  but  as  it  passes  over  the  borders 
it  assumes  a  papillary  character,  and  on  the  dorsum  it  is  covered 
with  papillae,  which  roughen  and  give  it  a  velvety  appearance. 
The  papillae  comprise  three  varieties  : — papillae  maximae,  calici- 
form,  or  circumvallate ;  mediae,  or  fungiform;  and  minimae,  or 
filiform. 

The  papillce  circumvallatoe,  three  to  five  in  number,  are 
situated  at  the  back  part  of  the  dorsum.  They  are  arranged 
triangularly,  the  single  one  being  posteriorly  and  mesially  placed, 
corresponding  to  the  foramen  caecum.  These  papillae  rest  in  cup- 
like depressions  of  mucous  membrane,  and  are  inversely  conical, 
with  the  apex  below  ;  several  such  papillae  may  be  enclosed  in 
the  same  calyx.  The  fungiform  papillcB  are  more  numerous, 
and  scattered  irregularly  over  the  dorsum,  being  most  numerous 
on  the  posterior  third ;  they  are  attached  by  a  narrow  neck,  the 
base  being  round,  free,  and  often  furnished  with  filiform  papillae. 
The  filiform  papillcB  cover  the  greater  part,  but  especially  the 
anterior  two-thirds  of  the  dorsum,  vanishing  towards  the  base. 
They  are  simple  or  compound,  the  former  having  one  free  pro- 
cess, the  latter  more  than  one.  Papillae  are  processes  of  the 
corium  of  the  mucous  membrane,  containing  terminal  nerve 
filaments,  numerous  in  the  larger,  but  difficult  to  trace  in  tha 


PAEOTID    GLAND. 


285 


-smaller,  papillge.  Like  the  mucous  membrane,  they  are  covered 
hy  a  thick  layer  of  squamous  epithelium,  which  is  sometimes 
imbricated.  It  is  generally  believed  that  the  caliciform  papillae 
are  subservient  to  the  special  sense  of  taste ;  that  the  fungiform 
variety  possesses  common  sensibility  ;  while  the  filiform  papillae 
serve  a  mechanical  purpose  during  the  action  of  the  tongue  on 
the  food. 

The  blood-supply  of  the  tongue  comes  from  the  lingual  and 
sublingual  branches  of  the  glosso-facial  artery,  and  the  blood  is 
returned  by  the  lingual  or  ranine,  and  sublingual  veins. 

The  principal  nerves  are — the. lingual,  or  gustatory  branch  of 
the  fifth ;  the  lingual  branch  of  the  glosso-pharyngeal ;  and  the 
hypoglossal  or  twelfth  pair. 


Parotid  and  molar  glands  of  the  left  side,    a  a,  Parotid  gland  ;  h  b,  Steno's  duct ;  c,  Superior, 
and  d.  Inferior  molar  glands. 

SALIVARY    GLANDS. 

The  salivary  glands  are  accessories  of  the  mouth.  They 
secrete  the  saliva,  which  is  discharged  into  the  mouth,  and 
saturates  the  food,  during  mastication.  There  are  three  primary 
pairs — viz.   the  Parotid,  the  Submaxillary,  and  the  Sublingual. 


PAROTID    GLAND. 


This,  the    largest  of  the  salivary  glands,  is  long  and  flat,  and 
is  situated  in  the  space  bounded  by  the  posterior  border  of  the. 


286 


SPLANCHNOLOGY. 


inferior  maxilla  and  tlie  anterior  border  of  the  wing  of  the  atlas  i 
it  lies  immediately  below  the  ear,  which  it  partly  surrounds,  and  is 
covered  by  the  deprimens  aurem.  It  is  related  internally  with 
the  guttural  pouch,  and  inferiorly  it  occupies  the  angular  space 
formed  by  the  jugular  and  glosso-facial  veins.  It  is  greyish,  and, 
like  all  salivary  glands,  conglomerate,  consisting  of  a  number  of' 
lobes  held  together  by  dense  areolar  tissue,  these  again  consist- 
ing of  lobules,  each  of  which  is  formed  by  minute  vesicles, 
originating  in  the  dilatation  of  the  branched  origins  of  th^' 
ducts.  The  latter  unite  t^  form  larger  ones,  and  terminate  in 
Steno's   duct,    which   commences  at  the  antero-inferior   surface. 


Fig.  92. 

Right  infero-lateral  view  of  the  head  ;  the  maxillary  ramus,  cheek,  parotid  gland,  and  upper  lip 
Leing  removed,  a,  Submaxillary  gland  ;  b,  Wharton's  duct ;  c,  Sublingual  gland  ;  d,  Its  excretory 
orifices ;  e  e,  Labial  glands  ;  /,  Their  excretory  orifices  ;  g,  Papilla,  with  orifice  of  Steno's  duct  ; 
h.  Orifices  of  the  superior,  and,  i,  those  of  the  inferior  molar  glands  ;  k,  The  hard  palate ;  I,  The  soft 
palate ;  to,  The  tongue,  with  its  papilla  ;  n,  Pillars  of  the  tongue  and  soft  palate ;  o,  Fraenum- 
linguse. 


near  the  insertion  of  the  sterno-maxillaris,  passes '  along  the 
posterior  aspect  of  the  digastricus,  round  the  ramus  of,  the 
lower  jaw,  in  company  with,  and  posterior  to,  the  glosso-facial 
artery  and  vein ;  it  thus  runs  along  the  anterior  border  of  the 
masseter,  and  enters  the  mouth  at  about  the  level  of  the  third 
upper  molar  tooth,  the  orifice  of  the  duct  being  marked  by  a 
papilla  on  the  buccal  membrane.  In  some  animals  there  is  a 
small  detached  gland  connected  with  it,  the  glandula  soda  paro- 
tidis,  which  opens  into  the  parotid  duct  as  it  crosses  the  masseter. 
The  duct  consists  of  an  internal  mucous  and  an  external  con- 
tractile coat. 


MINOR    SALIVARY    GLANDS.  28^ 

The  parotid  gland  is  supplied  with  blood  by  numerous  small 
arteries  given  off  from  larger  vessels  in  the  immediate  neighbour- 
hood. The  nerves  come  from  the  carotid  plexus,  also  from  the 
fifth  and  seventh  pairs. 

SUBMAXILLARY   GLAND. 

This  gland,  smaller  than  the  parotid,  is  long,  thin,  and  cres- 
centic,  with  the  concavity  directed  forwards  and  upwards.  It 
lies  in  the  maxillary  space,  below  and  behind  the  parotid,  and 
on  the  outer  side  of  the  pharynx,  extending  from  the  wing  of 
the  atlas  to  the  body  of  the  hyoid  bone,  where  it  terminates  in 
Wharton's  duct,  which  passes  between  the  mylo-hyoid  and 
hyo-glossus  brevis,  and  is  continued  along  the  side  of  the  jaw 
between  the  hyo-glossus  longus  and  the  sublingual  gland,  open- 
ing into  -the  mouth  rather  in  front  of  the  frsenum  linguo3,  where 
it  is  protected  by  a  thick  papilla  on  the  mucous  membrane, 
commonly  called  the  harh.  In  structure  it  is  similar  to  the 
parotid,  but  its  lobes  are  larger,  its  attachments  looser,  and  its 
duct- coats  thinner. 

LUce  the  parotid,  this  gland  receives  many  small  arteries  ;  they 
come  mostly  from  the  external  carotid  and  glosso-facial.  The 
nerves  are  chiefly  from  the  carotid  plexus. 

SUBLINGUAL   GLAND. 

This  gland  is  smaller  than  the  last-named,  long,  flat,  and 
delicate.  Situated  under  the  tongue,  it  is  placed  longitudinally, 
with  its  edges  vertical,  and  included  between  the  mylo-hyoideus, 
hyo-glossus  longus,  and  genio-hyo-glossus  muscles  ;  its  superior 
border  reaches  the  mucous  membrane  of  the  floor  of  the  mouth  ; 
anteriorly  it  extends  to  the  maxillary  symphysis,  posteriorly  to 
the  hyoidean  spur  process.  In  the  horse  it  opens  by  from  fifteen 
to  twenty  small  ducts,  the  ducts  of  Rivinus,  which  are  arranged 
along  the  floor  of  the  mouth,  on  what  has  been  termed  the  sub- 
lingual crest,  each  duct  being  marked  at  its  opening  by  a  papilla. 

UnUke  the  salivary  glands  hitherto  described,  the  sublingual 
gland  has  a  special  artery  of  supply,  the  sublingual  artery  ;  its 
nerves  come  from  the  gustatory  nerve  and  carotid  plexus. 

MINOR   SALIVARY   GLANDS. 

Other  presumably  salivary  glands  are  the  Molar,  the  Labial, 
the  Lingual,  and  the  Staph ylihe.     The  Molar  glands,  so  called 


288  SPLANCHNOLOGY. 

"because  they  are  parallel  to  the  rows  of  molar  alveoli,  are  two 
in  number,  superior  and  inferior  ;  they  are  situated  in  the  cheek, 
along  the  upper  and  lower  borders  of  the  buccinator.  They  dis- 
charge by  numerous  orifices  in  the  buccal  membrane.  The  Labial 
glands  are  placed  under  the  mucous  membrane  of  the  lips, 
especially  of  the  upper  one.  The  Lingual  glands  are  found  at  the 
base  of  the  tongue,  and  partly  along  its  sides.  The  Staphyline 
are  situated  in  the  soft  palate,  and  between  its  anterior  and 
posterior  pillars,  discharging  into  the  mouth  or  isthmus  faucium. 


Saliva,  the  fluid  secreted  by  these  glands,  is  clear,  viscid, 
colourless,  and  slightly  saline  in  taste,  with  a  specific  gravity  of 
1-005.  Alkaline  in  reaction,  it  consists  of  water  with  about 
■  one-half  per  cent,  of  solids,  including  fat,  albumen,  and  a  special 
nitrogenous  principle,  ptyalin,  or  "  animal  diastase,"  which  helps 
to  convert  starchy  material  into  grape  sugar.  Saliva  also  con- 
tains alkaline  and  earthy  salts,  with  a  trace  of  sulphocyanide  of 
potassium.  The  secretion  of  the  different  glands  varies  ;  that  of 
the  parotid  is  most  watery,  while  that  of  the  submaxillary  and 
sublingual  is  viscid.  The  parotid  secretes  most  abundantly  during 
mastication,  and  always  in  direct  ratio  to  the  dryness  of  the  food  ; 
the  others  secrete  equally,  whether  the  aliment  be  dry  or  moist, 
but  appear  to  be  influenced  by  its  taste.  The  sight  or  thought 
of  food  will  frequently  induce  a  secretion  from  the  submaxillary 
and  sublingual  glands. 

The  food  thus  becomes  saturated  in  the  mouth  with  two  fluids, 
-mucus  and  saliva,  both  assisting  in  mastication  and  deglutition,  the 
Jatter  in  addition  acting  upon  the  starchy  constituents  of  the  food. 

TEETH. 

Teeth  are  objects  implanted  in  and  protruding  from  the  maxil- 
lary alveoli.  They  are  characterised  by  the  hardness  and  density 
of  their  specific  tissues.  Like  bone,  these  tissues  consist  of  earthy 
salts,  with  a  basis  of  organic  animal  matter.  They  are  harder 
than  bone,  which  contains  about  67,  while  teeth  contain  76 i, 
23er  cent,  of  earthy  salts.  One  material  physical  difference 
between  a  bone  and  a  tooth  is  that  the  free  portion  of  the  latter 
bears  exposure  and  friction  with   impunity,  while  the  former  can 


TEETH.  ^  289" 

endure  neither  without  becoming  diseased.  Teeth  vary  with  the 
class  of  animal  in  number,  size,  form,  structure,  position,"  and 
attachment,  but  in  all  cases  they  are  in  correlation  with  the  food 
and  generic  habits  of  the  animal.  Thus,  in  herbivora,  where 
grinding  the  food  is  necessary,  the  contacting  surfaces  of  the 
molars  are  rough  and  flat.  In  carnivora,  where  tearing  and 
crushing  are  requisite,  the  molars  are  sharp,  pointed,  and  serrate ; 
in  omnivora,  where  the  food  is  general,  the  teeth  are  mixed  in 
their  character.  The  form  of  the  teeth  thus  depends  upon  the 
natural  food  of  the  animal,  and  there  is  always  a  certain  harmony 
between  their  disposition  and  the  conformation  of  correlated 
organs.  They  are  not  found  in  all  animals.  Birds  have  none, 
while  the  typical  number  of  mammalian  teeth  as  viewed  by  Pro- 
fessor Owen  is  forty-four. 

Three  hard  structures  enter  into  the  formation  of  the  teeth — 
Dentine,  or  Ivory ;  Enamel ;  and  Cementum,  or  Crusta  petrosa. 


DENTINE. 


Dentine  constitutes  the  major  part  of  the  tooth,  and  is  a 
hard,  yellowish  substance,  consisting  of  very  minute  tubuli  em- 
bedded in  a  dense,  granular,  intertubular 
matrix,  which  contains  the  bulk  of  the 
earthy  matter,  the  latter  being  about 
thirty  per  cent,  of  the  whole.  The 
tubuli  commence  at  the  pulp  cavity,  and 
radiate  to  the  superficies  of  the  dentine, 
where  they  anastomose  and  their  branches 
terminate  in  minute  cavities,  the  dentinal 
cells,  which  perhaps  are  analogous  to  the 
lacunce  of  bone.      The  tubuli  are  about 


the 


of  an  inch  in  diameter,   and. 


40^00 

in  the  fresh  state,  they  contain  processes 


Oblique  section  of  dentine,  show- 
ing the  tubuli  and  coalescence  of 
the  calcified  nodules. 


from  the  pulp. 

During  the  development  of  a  tooth 
the  calcification  of  the  dentine  proceeds  from  centres,  around 
which  tite  calcific  material  becomes  deposited.  Thus  nodules  are 
formed,  which,  by  expanding,  finally  coalesce  and  form  the  solid 
matrix. 


290 


SPLANCHNOLOGY. 


ENAMEL. 

In  appearance  enamel  is  distinguislied  by  its  peculiar  white- 
ness.     It  is  the  hardest  animal  texture,  containing  about  9G  per 
cent,  of  earthy  salts.      It  consists  of  hexagonal  prisms,  which  are 
arranged  side  by  side,  with  one  extremity  resting  on  the  surface 
A  of  the  dentine,  whence  they 

are  disposed  in  gently  wav- 
ing lines  towards  the  surface 
of  the  tooth.  They  vary 
somewhat  in  diameter,  but 
average  ^^jj-q  of  an  inch. 
No  nutrient  vessels  ornerves 
have  been  traced  into  ena- 
mel, and  when  destroyed  it 
is  not  reproduced. 

This  tissue  is  protective, 
sometimes  covering  the  entire  exposed  surface  of  the  tooth,  as  in 
the  human  subject  and  the  dog,  and  it  also  furnishes  the  rough 
projections  and  cutting  edges  found  in  the  teeth  of  some  classes 
of  animals,  the  herbivora  affording  the  best  example  of  this. 


Fig.  94. 
A,  Transverse  section  of  enamel,  showing  the  cut 
ends  of  its  hexagonal  prisms  ;  B,  Prisms  separated. 


CRUSTA  PETROSA. 

Crusta  Petrosa,  or  cementum,  the  third  constituent,  completely 
covers  the  imbedded  portion  of  the  tooth,  and  occupies  the  cavities 
on  the  free  portion,  where  such  exist.  It  is  thickest  towards  the 
roots,  most  abundant  on  the  molar  teeth,  and  is  distinguished  by 
its  brownish-yellow  colour.  It  is  the  softest  dental  texture, 
closely  resembling  true  bone  in  structure,  having  tubuli  and  cells 
resembling  the  canaliculi  and  lacunae,  and  where  it  is  thick  it 
may  be  traversed  by  vascular  tubes  analogous  to  the  Haversian 
■canals.  The  proportion  of  earthy  matter,  the  same  as  in  bone, 
is  about  67  per  cent. 


ARRANGEMENT  AND  KINDS  OF  TEETH. 

Teeth  may  be  simple  or  compound.  Simple  as  in  the  dog, 
^here  the  entire  exposed  surface  is  covered  by  a  solid  cap  of 
enamel,  which  alone  is  in  wear  ;  compound  or  complex,  as  in  the 
horse,  where  various   tissues  are   in  wear.      A  tooth   consists   of 


INCISOR    TEETH.  291 

1:he  following  anatomical  parts ;  the  body,  or  crown,  which  is  free 
of  the  gum,  the  grinding  or  cutting  surface  of  which  is  the  table ; 
the  cervix,  or  neck,  the  part  invested  by  the  gum  ;  and  the  fang, 
or  root,  which  is  inserted  into  the  socket  or  alveolus.  The 
alveoli  are  more  porous,  spongy,  and  vascular  than  other  bone  ; 
they  appear  and  grow  with  the  teeth,  and  when  these  decay, 
become  absorbed.  They  are  lined  by  periosteum,  which, 
reflected  from  the  gum,  at  the  base  of  the  socket,  covers  the 
fang,  communicating  with  the  pulp  cavity,  which  runs  up  the 
fang  centre,  and  contains  a  highly  vascular  and  nervous  organ, 
the  jjuljy,  whence  the  dentine  of  the  tooth  grows.  This  pulp  is 
enclosed  in  a  vascular  membrane,  the  dentine  tubuli  radiating 
from  it.  In  the  aged  tooth  this  membrane  becomes  ossified, 
forming  the  secondary  or  osteo-derdine.  The  sensory  nerve  of 
the  pulp  comes  from  the  fifth  pair ;  and  it  is  owing  to  its 
extreme  sensibility  that  toothache  is  so  severe  when  tjie  pulp  is 
exposed. 

Teeth  are  arranged  alongside  of  each  other,  so  as  to  form  the 
dental  arches  :  these  are  interrupted  at  each  side,  leaving  the 
interdental  spaces,  or  diastemce.  Teeth  are  of  three  kinds  ;  the 
Incisors,  or  cutting  teeth,  situated  in  front  of  the  arches  ;  Canine 
teeth,  or  tushes,  in  the  interdental  spaces;  and  Molars,  or  grinders, 
behind.  The  horse,  like  many  other  animals,  has  two  sets  ;  the 
temporary  or  milk  teeth,  and  the  permanent  or  horse  teeth,  the 
former  numbering  24,  the  latter  40.  In  the  mare  there  are 
usually.  36  permanent  teeth,  the  tushes  being  wanting  or  rudi- 
mentary. 

INCISOR  TEETH. 

The  incisor  or  front  teeth  in  the  horse  are  12  in  number,  6 
in  each  jaw  ;  the  upper  ones  are  the  longer,  their  surfaces  meet- 
ing those  of  the  lower  ones  ;  in  rare  cases  the  former  overlap, 
constituting  a  "  parrot  mouth."  The  central  pair  are  the  largest, 
the  adjacent  ones  are  called  the  middle,  or  lateral,  while  the 
outer  ones,  which  are  the  smallest,  are  termed  the  corner  incisors. 
The  row  of  incisors  forms  a  curve,  which  is  part  of  the  so- 
called  dental  arch;  the  younger  the  tooth  the  greater  the 
curvature,  which  gradually  decreases  with  age.  The  anterior 
surface  of  a  young  incisor  tooth  presents  a  triangular  shape,  with 
the  base  at  the  table.      Viewed  laterally  it  is  still  triangular,  but 


292 


SPLANCHNOLOGY. 


A 

Fig.  95. 

Incisor  and  canine  teeth  of  a 

Horse.     A,  Front,  B  B,  Lateral, 

and  C  C,  Corner  incisors;  D  J), 

Canine  teeth. 


its  apex  is  at  the  table.  Tbe  table  is  therefore  oblong,  its  long 
axis  following  the  line  of  the  dental  arch.  As  it  wears,  it  narrows 
laterally,  but  its  short  axis  widens,  until  in  old  age  it  is  nearly 
round,  what  was  the  fang  being  in  wear. 
The  free  surface  of  an  incisor  tooth, 
excepting  the  table,  is  covered  by  a  layer 
of  enamel ;  the  fang,  which  is  a  single 
process,  being  covered  by  crusta  petrosa. 
Towards  the  centre  of  the  table,  in  a 
young  tooth,  a  second  ring  of  enamel  is 
visible,  which  is  the  mouth  of  a  funnel- 
shaped  cavity  called  the  infundibulum. 
This  cavity  in  the  young  animal  is  ovoid, 
its  long  axis  following  that  of  the  table  ; 
it  is  lined  by  crusta  petrosa,  which,  be- 
coming stained  by  the  food,  constitutes, 
tbe  so-called  "  mark."  The  space  be- 
tween the  two  tubes  of  enamel  is  filled 
up  with  dentine  ;  hence  the  table  is  a  comnound  one — i.e.,  all 
three  of  the  dental  tissues  are  in  wear  on  it 

The  infundibulum,  or  mark,  being  conical 
in  shape,  wears  with  the  tooth,  becomes  smaller, 
and  ultimately  vanishes.  For  example,  the 
permanent  central  incisors  are  up  at  three 
years;  in  the  lower  jaw  the  infundibulum 
wears  away  about  one-third  in  each  year;  the 
animal  will  probably,  therefore,  be  six  years 
of  age  when  the  mark  is  gone  from  the  central 
incisors.  Sometimes  the  cavity  is  absent,  its 
place  being  occupied  by  crusta  petrosa  ;  still, 
in  the  centre  of  the  tooth  there  is  the  inner 
ring  of  enamel.  Thus,  in  the  transverse  sec- 
tion of  a  young  tooth,  we  notice  an  outer  and 
an  inner  ring  of  enamel,  the  interspace  being 
filled  by  a  mass  of  dentine,  and  the  inner  ring 
lined  by  crusta  petrosa  (see  Fig.  96). 

In  the  centre,  the  table  in  front  of  the 
infundibulum  is  broader  than  that  behind  it, 
and  as  the  tooth  wears  it  still  broadens.  In  this  space 
sometimes  a  spot  is  apparent  which  differs  from  the  rest  of 
the  dentine  ;  it  is  the  osteo-dentine  covering  the  pulp  cavity  ;  this. 


Fig 

Incisor  tooth  of  a 
.Horse  —  posterior  view. 
a,  Outer  layer  of  enamel; 
6,  Inner  layer  of  enamel 
round  the  infundibulum; 
c,  Dental  star;  d,  The 
dentine. 


MOLAR    TEETH.  293 

object  has  been  termed  the  dental  star.  The  corner  teeth  may 
have  no  posterior  tables,  constituting  shell  teeth  ;  rarely  they  are 
absent  in  every  tooth  whea  we  have  a  shell  mouth.  The  incisor 
rtiilk  teeth  are  whiter  than  the  permanent  ones,  and  have  distinct 
necks,  the  necks  of  the  latter  being  imaginary.  They  are  convex 
and  grooved  posteriorly,  and  have  their  dentine  stained.  Almost 
perpendicular  to  the  axis  of  the  head,  in  the  young  animal,  the 
incisors  become  more  and  more  horizontal  as  the  animal  ages. 
Permanent  incisors  are  convex  anteriorly,  the  lower  incisors  having 
one,  the  superior  two  grooves  down  the  centre  of  the  body ;  these 
are  filled  with  cementum,  but  are  absent  in  old  teeth.  The 
incisor  teeth  attain  their  greatest  development  in  the  elephant, 
in  which  animal  they  project  from  the  mouth  as  tusks,  it  may  be 
to  an  enormous  extent. 

CANINE   TEETH. 

The  tushes,  tusks,  or  canine  teeth,  well  developed  in  dogs  and 
other  carnivora,  are  simple  teeth,  four  in  number,  a  pair  above 
and  below.  They  rest  in  the  interdental  spaces,  the  lower  being 
nearer  the  incisors  than  the  upper  ones ;  they  are  permanent  ab 
initio,  and  appear  between  the  fourth  and  fifth  year,  sometimes 
a  year  in  advance.  The  crown  is  somewhat  conical,  the  base  being 
at  the  gums.  The  external  surface  is  convex,  and  marked  by 
several  fine  longitudinal  lines  ;  the  internal  surface  presents  on 
either  side  a  sharp  ridge  which  separates  it  from  the  external. 
The  crown  terminates  in  a  conical  eminence,  somewhat  hollowed 
internally  during  growth,  and  bounded  by  a  sharp  ridge.  When 
a  tusk  has  been  long  in  wear,  the  ridge  disappears,  and  the 
internal  surface  becomes  nearly  smooth ;  and  as  the  apex  of  the 
tooth  becomes  worn  away,  often  a  small  mark  appears,  but  no 
second  ring  of  .enamel.  These  teeth  have  no  constricted  neck, 
and  the  fang  is  single.  In  the  horse  tribe,  as  a  rule,  canine  teeth 
are  developed  only  in  the  male ;  if  they  exist  in  the  female  they 
are  rudimentary. 

MOLAR    TEETH. 

The  Molars,  or  grinders,  are  12  in  the  temporary  set,  3  on 
either  side  of  each  jaw;  24  in  the  permanent  set,  6  on  each  side 
above  and  below ;  they  are  numbered  from  before  backwards, 
and,  like  the  incisors,  those  of  the  upper  jaw  are  the  larger. 

A  molar  tooth  is  constructed  on  the  same  general  plan  as  an 


A 
Fia.  97. 


294  SPLANCHNOLOGY. 

incisor,  but  the  contour  of  the  various  parts  is  much  more 
irregular.  There  are  generally  two  infundibula  containing  a 
large  quantity  of  cementum,  a  layer  of  which  also  covers  the 
g^reater  part  of  the  external  enamel. 

The  crown  of  the  upper  molars  is  somewhat  cubic ;  their 
external  surface  presents  two  grooves  running  from  table  to 
root,  the  anterior  being  the  deeper. 
The  crown  of  the  lower  molars  is 
narrower,  but  longer  than  that  of  the 
upper  ones,  and  has  only  one  groove. 
The  inner  surface  of  the  upper  molars 
is  not  so  deep  as  the  outer,  while  the 
inner  surface  of  the  lower  ones  is  the 
deeper ;  the  two  lower  rows  diverge 
towards  the  back  of  the  mouth,  while 
the  two  upper  rows  are  rather  convex 
Transverse  8ection"'of  a  molar  tooth,  externally.  The  molar  grinding  sur- 
A  A,  External  crusta  petrosa;  B,  Exter-  face  is  Very  irrcsfular,   owinof  to    the 

nal  enamel;  C  C,  The  dentine;  D  D,  •    -ii       i         i  C     • 

Internal  enamel  surrounding  the  infun.    Variable    hardueSS    of     itS    COmponentS. 

Snf;nYbui'a™^'''^'""°"'^^^"'  ^     horse    may    have     supplementary 
molars,    or    wolf    teeth ;     these     are 
small,   and  placed  one  on  each  side  of  the  jaw,  anterior  to  the 
first  molars  ;  they  are  usually  shed  with  the  milk  teeth. 

The  teeth  which  replace   the  deciduous  or   milk   molars   are 
situated  anteriorly,  and  are  termed  in  general  zootomy  premolars. 


DENTAL    FORMUL-E. 

A  dental  formula  expresses  in  a  concise  manner  the  number 
and  position  of  the  teeth  possessed  by  an  animal.  The  numbers 
are  written  somewhat  in  the  form  of  fractions,  and  prefixed  are 
the  initial  letters  of  the  names  of  the  various  teeth.  Thus,  i. 
stands  for  incisors,  c.  for  canines,  p.m.  for  premolars,  and  m,  for 
molars.      For   example,  the  molar  teeth  of  the   dog  are   thus 

2-2 
represented  : — m.  o^^  ;  this  means  that  there  are  two  molars  on 

each  side  in  the  upper  jaw,  and  three  on  each  side  in  the  lower 

jaw.     In  the  ox  the  incisors  are  i.  5 —  ,  or  none  whatever  in  the 

0  —  0 

upper,  and  three  on  each  side  in  the  lower  jaw.     The  full  dental 

formulae  of  the  horse  are  as  follows  : — 


DEVELOPMENT    OF    THE    TEETH.  295 

Deciduous  or  milk  teeth. 
.  3-3        0-0          3-3_12_ 
^-  3^:3'  ^'  0~0'  '^'  3^~12"^*- 

Permanent  teeth. 
.3-3        1-1.  3-3         3-3     20     ,^ 

*•  3~3'  '•  rri'  V-^""-  3-:r3'  ^^-  3-3  =  20=*^- 

DEVELOPMENT    OF    TH3    TEETH. 

The  development  of  the  teeth,  as  demonstrated  by  the  late 
Professor  Goodsir,  consists  of  three  distinct  stages — papillary, 
follicular,  and  saccular.  About  the  sixth  week  of  foetal  life  a  depress- 
sion  is  formed  in  the  mucous  membrane  of  the  gum,  which  is  the 
primitive  dental  groove,  from  the  floor  of  which  arise  papillae  or 
processes  corresponding  numerically  to,  and  constituting  the  gerin^ 
of,  the  milk  teeth ;  this  is  the  papillary  stage.  About  the  tenth 
week  the  groove  deepens,  the  papillae  enlarge,  the  margins  of  the 
grooves  thicken  and  become  prominent ;  prolongations  or  septa 
pass  from  one  side  of  the  groove  to  the  other,  enclosing  each 
papilla  in  an  open  follicle  or  sac  ;  this  constitutes  the  follicular 
stage  ;  it  terminates  about  the  fourteenth  week.  Somewhat  later, 
the  papillae  begin  to  assume  the  shape  of  the  crowns  of  the  future 
teeth.  Small  membranous  processes  or  opercula  are  now  developed 
firom  the  sides  of  the  follicle,  which  correspond  in  number  and 
shape  with  the  table  surfaces  of  the  teeth ;  thus,  for  the  incisors, 
there  is  one  on  either  side,  the  tushes  have  three,  and  the  molars 
four  or  five,  according  to  their  size  and  situation.  The  lips  of 
the  follicles,  as  well  as  the  opercula,  close  and  cohere,  and  the 
grooves  becoming  obliterated,  what  were  open  follicles  are  con- 
verted into  closed  sacs,  thus  completing  the  saccular  stage. 
Shortly  before  the  closing  of  the  follicles  of  the  milk  teeth,  a 
lunated  depression  is  noticed  behind,  and  to  the  inner  aspect  of 
each  follicle ;  these  become  converted  into  cavities  of  reserve, 
which  ultimately  form  sacs  for  the  development  of  the  permanent 
incisors,  as  well  as  the  three  anterior  permanent  molars.  The 
dental  sac,  as  well  as  the  enclosed  papilla,  continues  to  enlarge, 
the  papilla  becoming  converted  into  the  pulp,  and  acquiring  the 
semblance  of  the  dental  crown.  The  contents  of  the  sac  now 
consist  of  the  vascular  pulp,  covered  by  its  membrane — an  internal 
vascular  layer,  lining  the  sac,  called  the  periodontal  membrane  ; 
and  a  fluid  lying  between   the   two   membranes,   the   outer    or 


296  SPLANCHNOLOGY. 

enamel  pulp.  The  process  of  calcification  now  commences.  A. 
thin  lamina  or  cap  of  dentine  is  first  developed  on  the  outer  and 
most  prominent  part  of  the  pulp,  from  its  covering  membrane  ; 
this  continues  to  be  formed  by  the  substance  of  the  pulp,  which 
gradually  decreases  as  the  dentine  increases,  the  enamel  being, 
at  the  same  time,  deposited  in  crystals  from  its  own  peculiar  or 
outer  pulp.  The  cementum  also  forms  pari  passu,  from  the 
calcification  of  the  periodontal  membrane  lining  the  sac.  When 
calcification  of  the  dental  textures  is  sufficiently  advanced,  the 
tooth  makes  its  way  through  the  gum,  which  is  absorbed,  as  the 
crowns  are  forced  upwards  by  the  growth  of  their  fangs.  The 
septa  or  divisions  between  the  dental  sacs  now  ossify,  and  con- 
stitute the  alveoli.  As  growth  continues,  the  base  of  the  pulp 
contracts  and  forms  the  neck.  The  dental  sac  now  elongates,  and 
gradually  becomes  less,  owing  to  the  formation  of  dehtine  on  its 
outer  surface,  until  only  a  small  cavity  is  left  in  the  centre,  in 
which  rests  the  pulp  and  its  vessels.  In  the  molars,  every  point  on 
the  crown  has  a  separate  cap  of  calcification.  These  enlarge,  and 
finally  meet.  In  the  formation  of  the  molar  fangs  the  pulp  divides, 
ossification  in  each  section  proceeding  as  in  a  singie-fanged  tooth. 
The  permanent  teeth  are  developed  like  the  temporary  ones. 
As  the  permanent  tooth  continues  to  grow,  it  gradually  presses 
on  the  milk  tooth,  and  ensures  absorption  of  its  roots,  until  the 
entire  fang  becoming  removed,  the  crown  of  the  milk  tooth  falls 
out,  and  the  permanent  tooth  appears  above  the  gum.  The 
remaining  permanent  teeth,  the  three  posterior  molars  in  each  side 
of  either  jaw,  are  developed  thus  : — Behind  the  third  molars 
there  is  a  portion  of  the  dental  groove  unobliterated,  which  forms 
a  cavity,-  called  the  posterior  cavity  of  reserve,  in  which  a  papilla 
appears,  and  undergoes  the  same  change  as  that  of  the  temporary 
teeth,  forming  the  rudiment  of  the  fourth  molar.  From  this 
cavity  is  developed  a  second  follicle  for  the  fifth,  and  from  this 
the  follicle  of  the  sixth  or  last  molar. 


PHAEYNX. 

The  pharynx  is  a  musculo-membranous  cavity  common  to  'the 
digestive  and  respiratory  canals.  Somewhat  cylindrical  in  the 
horse,  it  extends  obliquely  downwards  and  backwards,  and  lies 
behind  the  velum  palati,  which  separates  it  from  the  mouth,  an4. 
forms  its  anterior  wall.      It  is  attached  superiorly  to  the  base  of 


PHARYNGEAL   MUSCLES.  297 

the  cranium  by  muscles  and  aponeurosis,  infero-laterally  to  the 
Jaiynx,  and  infero- posteriorly  it  is  continuous  with  the  oesophagus. 
It  communicates  with  other  cavities  by  seven  openings — viz.,  the 
%^o  posterior  nares  superiorly ;  posteriorly,  on  either  side,  with  the 
slit-like  openings  of  the  Eustachian  tubes,  which  lead  to  the 
guttural  pouches,  and  are  guarded  by  a  cartilaginous  valve ; 
anteriorly,  below  the  posterior  nares,  is  the  isthmus  of  the  fauces, 
leading  into  the  mouth,  and,  excepting  during  deglutition,  closed 
by  the  velum  palati  ;  inferiorly,  behind  the  root  of  the  tongue,  is 
the  opening  of  the  larynx,  and  behind  this  tbe  oesophagus.  The 
walls  of  the  pharynx  consist  of  a  muscular  layer,  with  a  lining  of 
mucous  membrane. 

PHARYNGEAL  MUSCLES. 
The  muscular  layer  of  the  pharynx  is  separable  into  seven  pairs 
of  muscles.  These  are  best  seen  posteriorly,  where  they  appear 
as  a  series  of  flattened,  fleshy  bands,  the  superior  of  which  meet 
their  fellows  of  the  opposite  side  at  a  mesian  vertical  line  or  raphe. 
The  names  of  the  muscles  are  as  follows,  and,  excepting  the  first 
a,nd  last,  they  are  named  in  order  from  above  downwards  : — 


Pharyngo-staphylinus. 

Pterygo-pharyngeus. 

Kerato-pharyngeus. 


Hy  o-phary  ngeu  s. 

Thyro-pharyngeus. 

Crico-pharyngeus. 


Aryteno-pharyngeus. 
PHARYNGO-STAPHYLINUS. 

(See  Muscles  of  the  soft  palate.) 

PTERYGO-PHARYNGEUS. 

(Fig.  90.  I.) 

This  is  a  thin,  broad  band  of  muscle  arising-  from  the  pterygoid 

process.     Its  fibres  are  directed  backwards  and  downwards.     It 

terminates  by  meeting  its  fellow  at  the  posterior  median  line  of 

the  pharynx,  of  which  cavity  it  is  a  constrictor. 

KERATO-PHARYNGEUS. 
(Fig.  90.  m.) 

Arising  from  the  inner  aspect  of  the  hyoid  comu,  this  muscle, 
A  small,  narrow  band,  runs  inwards  and  downwards  to  the  wall  of 
the  pharynx,  becoming  blended  with  the  pterygo-pharyngeus.  It 
is  a  levator,  and  by  some  considered  a  dilator  of  the  pharynx. 


298 


SPLANCHNOLOGY. 


HYO-PHARYNGEUS. 
(Fig.  90.  n.) 

This  is  a  flat  muscle  arising  from  the  heel  process  of  the  hyoicJ 
bone,  and  slightly  from  the  thyoid  cartilage  of  the  larynx.  Its 
fibres  passing  upwards  and  backwards,  it  reaches  its  fellow  of  the 
opposite  side  at  the  posterior  median  line.     It  is  a  constrictor. 

THYEO-PHARYNGEUS. 

(Fig.  90.  o.) 

Placed  immediately  below  the  muscle  last  described,  this- 
muscle  joins  its  fellow  in  a  similar  manner,  arising  from  the- 
thyroid  cartilage.     It  also  is  a  constrictor. 

CRICO-PHARYNGEUS. 
(Fig.  90.  p.) 

Situated  below  the  thyro-pharyngeus,  this  muscle  arises  from 
the  lateral  aspect  of  the  cricoid  cartilage.  Its  fibres  run  back- 
wards, converging  slightly  upwards,  and  it  terminates  similarly- 
to  the  two  muscles  last  described,  its  action  resembling  theirs. 

ARYTENO-PHARYNGEUS. 

This  is  a  small  band  stretching  from  the  posterior  aspect  of 
the  arytenoid  cartilage  to  the  muscular  wall  of  the  cesophagus,^ 
its  action  being  to  raise  the  latter. 

The  pharynx  is  supplied  with  blood  by  the  pharyngeal  and 
thyro-laryngeal  arteries.  Its  nerves  are  derived  from  the  ninth 
and  tenth  pairs,  and  from  the  sympathetic.  Its  respiratory 
function  is  purely  a  passive  one,  while  what  may  be  termed  its 
alimentary  function  is  an  active  one,  to  assist  in  deglutition. 

(ESOPHAGUS. 

The  oesophagus,  or  gullet,  is  a  long  musculo-membranous 
cylindrical  canal,  passing  from  the  pharynx  to  the  stgmach, 
through  which  the  food  reaches  the  latter.  Originating  at  the 
lower  part  of  the  pharynx,  immediately  behind  the  aperture  of 
the  birynx,  it  descends  the  neck,  at  first  behind  the  trachea,  then 
inclines  to  the  left  of  it,  the  two  entering  the  thorax  together;  it 


(ESOPHAGUS.  29i) 

then  passes  lo  the  tipper  side  of  the  trachea,  over  the  base  of 
the  heart,  through  the  posterior  mediastinum,  and  through  the 
diaphragm  by  the  foramen  sinistrum ;  it  thus  gains  the  abdom- 
inal cavity,  and  terminates  in  the  cardiac  orifice  of  the  stomach. 
It  is  narrowest  at  its  origin  behind  the  larynx,  then  of  uniform 
size  until  it  reaches  the  diaphragm",  where  it  again  constricts. 

The  oesophagus  may  be  said  to  consist  of  a  cervical,  a  thoracic, 
and  an  abdominal  portion,  the  latter  being  very  short.  It  con- 
sists of  two  tunics,  an  internal  mucous  and  an  external  muscular, 
which  are  very  loosely  united  by  areolar  tissue.  The  mucous 
coat  is  continuous  with  that  of  the  pharynx  and  stomach,  but  is 
pale  in  colour,  and  clothed  with  dense  stratified  epithelium  ;  it 
presents  numerous  longitudinal  folds,  which  allow  of  considerable 
dilatation,  and  a  number  of  racemose  glands.  The  muscular 
coat  consists  of  an  external  longitudinal,  and  an  internal  circular 
layer  of  fibres.  The  cervical  and  anterior  thoracic  muscular  coat 
h  striated,  the  remainder  non-striated,  but  both  are  involuntary. 
The  longitudinal  layer  commences  by  three  fasciculi,  one  in  front 
and  one  on  either  side,  which  unite  to  form  a  continuous  layer. 
The  circular  fibres  originate  at  the  inferior  constrictors  of  the 
pharynx.  Posteriorly,  both  sets  of  fibres  pass  to  the  muscular 
coats  of  the  stomach. 

The  oesophagus  is  supplied  with  blood  anteriorly  by  twigs 
from  the  carotid,  and  the  broncho-cesophageal  arteries  posteriorly ; 
its  nerves  come  from  the  pneumogastric.  The  oesophagus  has 
no  other  use  than  for  the  conveyance  of  aliment  from  the 
pharynx  to  the  stomach.  Its  most  noteworthy  features  in  the 
horse  are, — first,  the  abrupt  manner  in  which  it  enters  the 
stomach,  hardly  dilating  at  all  before  doing  so ;  secondly,  the 
enormous  proportionate  size  of  its  mucous  membrane  posteriorly; 
this  is  so  large,  that  near  the  stomach  its  folds  completely  fill 
the  tube  when  empty,  thus  acting  as  a  valve,  and  preventing 
regurgitation  of  the  food. 

The  process  of  deglutition,  or  swallowing  the  food,  is  performed 
in  the  following  manner : — The  masticated  food  gathers  as  a 
bolus  at  the  root  of  the  tongue,  which  by  retracting  forces  the 
pellet  through  the  isthmus  faucium  into  the  pharynx  ;  the  velum 
pendulum  palati  recedes  backwards  and  upwards,  while  the  food 
forces  down  the  epiglottis,  effectually  closing  the  larynx ;  finally, 
the  pharynx,  by  its  constrictor  muscles,  grasps  the  bolus,  and 
presses  it  downwards  into  the  oesophagus.  ,  The  passage  of  food 


300 


SPLANCHNOLOGY. 


into  the  pharynx  is  purely  voluntary  ;  but  as  soon  as  it  enters 
the  oesophagus,  the  act  of  deglutition  is  entirely  involuntary,  the 
food  travelling  by  a  vermicular  or  peristaltic  motion,  caused  by 
the  circular  muscular  fibres  of  the  oesophagus  contracting  with 
successive  regularity. 


ABDOMEN. 

The  ultimate  organs  of  digestion  are  contained  in  the  abdomen, 
or  belly,  which  is  a  large  and  somewhat  ovoid  cavity,  bounded 
superiorly  by  the  muscles  of  the  sublumbar  region;  inferiorly  and 
laterally  by  the  abdominal  muscles  ;  and  anteriorly  by  the  dia- 
phragm ;  posteriorly  it  is  continuous  with  the  pelvic  cavity.  It 
contains  chiefly  the  stomach,  intestines,  and  kidneys,  with  their 
uccei^sories.  It  is  lined  by  the  peritoneum,  a  serous  membrane, 
which  is  reflected  over  the  viscera. 

For  convenience  of  description,  the  abdomen  is  divided  into 
nine  regions,  indicated  by  imaginary  lines  drawn  as  follows  : — ■ 
Two  transverse  lines  divide  it  into  three  primary  regions.  The 
first  line  is  drawn  from  the  cartilage  of  the  last  false  rib  on  one 
side,  to  that  of  the  other ;  the  second  unites  the  right  and  left 
anterior  iliac  spines.  These  divide  the  cavity  into  the  anterior 
or  epigastric,  middle  or  umbilical,  and  posterior  or  hypogastric 
regions.  These  regions  are  each  subdivided  into  three  secondary, 
or  right,  left,  and  central  regions,  by  two  longitudinal  lines, 
extending  from  either  side  of  the  ensiform  cartilage  to  about  the 
ilio-pectineal  eminences,  completing  the  division,  which  may  be 
tabulated  as  follows  : — 


Eight. 

Centbal, 

Left. 

Anterior. 

Middle. 
Posterior. 

Right  Hypochon- 
driac. 

Right  Lumbar. 

Right  iliac. 

Epigastric. 

Umbilical. 
Hypogastric. 

Left  hypochon- 
driac. 

Left  lumoar. 

Left  iliac. 

The  portion  of  the  alimentary  canal  contained  in  the  abdomen 
comprises  the  stomach  and  intestines. 


STOMACH. 


301 


STOMACH. 

The  stomach  is  a  dilatation  of  the  alimentary  canal,  continuous 
■with  the  oesophagus  and  small  intestine,  where  the  food  is  con- 
verted into  chyme,  by  maceration  and  the  action  of  the  gastric 
juice.  In  the  horse  it  is  small  in  proportion  to  the  size  of  the 
animal,  and  rests  in  the  left  hypochondriac  region,  stretching  when 
full  into  the  epigastric ;  when  distended,  it  resembles  a  bent  tube 
with  two  lateral  dilatations,  divided  by  a  central  constriction  into 
a  left,  or  cardiac,  and  a  right,  or  pyloric  portion.     The  former  is 


Fio.  98. 
Posterior  view  of  the  stomach  of  a  Horse,   a,  Left  eul-de-nac;  b.  Right 
eul-de-sac;  e.  Greater  curvature  ;  d.  Lesser  curvature  ;  e,  (Esophagus; 
/,  Duodenum. 

the  larger,  and  called  the  greater  cul-de-sac,  or  fundus;  the  right 
portion,  is  the  lesser  cul-de-sac,  or  antrum  pylori.  It  has  one 
opening  on  the  left,  leading  into  the  oesophagus,  through  which 
the  food  enters ;  this  is  the  cardiac  orifice ;  and  another  on  the 
right,  which  communicates  with  the  first  portion  of  the  intestine 
called  the  duodenum ;  this  is  the  pyloric  orifice.  At  the  pyloric 
orifice  there  is  a  constriction  called  the  pyloric  ring.  Between 
the  two  openings  the  upper  and  lower  borders  are  termed  the 
•curvatures,  the  superior  or  lesser  being  concave,  the  inferior  or 
greater  convex. 

The  curvatures    indicate  the  division  of  the  surface   of  the 
stomach    into  two  portions,  an  anterior   and  posterior.      The 


S02  SPLANCHNOLOGY. 

anterior  is  related  with  tlie  diaphragm  and  liver,  the  posterior  with- 
the  diaphragmatic  flexure  of  the  colon.  The  spleen  lies  along; 
the  inferior  and  external  part  of  the  greater  cul-de-sac,  its  base 
being  directed  backwards  and  somewhat  upwards  ;  the  pyloric 
extremity,  which  is  placed  lower  than  the  cardiac,  is  related  with 
the  right  lobe  of  the  liver  and  the  intestines. 

The  walls  of  the  stomach  are  composed  of  three  coats — an 
external  serous,  a  middle  muscular,  and  an  internal  mucous  coat. 

The  serous  coat,  a  reflection  of  the  peritoneum,  is  smooth  and 
elastic,  adhering  intimately  to  the  muscular,  except  at  the  lesser 
curvature,  where,  strengthened  by  addition  of  yellow  elastic  tissue, 
it  forms  a  ligament,  which  appears  to  support  the  two  extremities 
of  the  stomach  ;  forming  around  the  cardiac  orifice  a  circular 
fold,  which  surrounds  the  oesophagus  and  passes  to  the  dia- 
phragm ;  this  is  the  gastro-phrenic,  or  coronary  ligament 
The  peritoneum  also  passes  in  a  double  fold  from  the  greater 
curvature  to  the  spleen,  as  the  gastro-splenic,  to  the  colon  as  the 
gastro-colic,  or  great  omentum ;  and  from  the  lesser  curvature 
to  the  liver,  as  the  gastro-hepatio  omentum. 

In  the  m,uscular  coat  are  three  sets  of  fibres — an  external 
longitudinal,  a  middle  circular,  and  an  internal  oblique  layer. 
The  longitudinal  are  continuous  with  those  of  the  oesophagus, 
and  radiate  from  the  cardiac  orifice  ;  they  are  thickest  at  the 
curvatures,  and  are  thinly  scattered  over  the  surfaces ;  towards 
the  pyloric  end  they  again  converge,  and  form  a  uniform  layer^ 
which  is  continuous  with  that  of  the  duodenum.  The  middle 
layer  consists  of  circular  fibres,  which  cover  the  entire  organ  ; 
near  the  pylorus  they  thicken  into  a  circular  ring,  which  projects 
into  the  orifice,  and  forms  with  a  doubling  of  the  mucous  mem- 
brane, a  sphincter,  called  the  pyloric  valve,  which  by  contraction 
prevents  crude  food  from  passing  into  the  intestine.  The  inner 
layer,  is  composed  of  oblique  fibres,  continuous  with  the  circular 
oesophageal  ones  ;  they  are  confined  to  the  cardiac  portion, 
descend  obliquely  over  either  surface,  and  disappear  towards  the 
central  constriction.  All  these  layers  are  composed  of  pale  or 
involuntary  tissue;  the  longitudinal  layer,  by  contracting,  enables 
the  stomach  to  dilate ;  the  circular  produces  vermicular  motion, 
while  the  oblique  layer  tends  to  force  the  food  from  the  left  into 
the  right  cavity ;  thus  there  is  produced  a  kind  of  churning 
motion,  which  macerates  the  food  and  brings  each  portion  of  it- 
into  contact  with  ths  mucous  surface. 


STOMACH.  303^ 

The  internal,  or  mucous  coat,  is  divided  into  right  and  left 
portions.  The  latter  is  the  cuticular  portion,  continuous  with 
the  mucous  membrane  of  the  oesophagus,  which  it  resembles  in 
structure  and  appearance;  it  is  covered  by  a  thick  layer  of 
stratified  epithelium.  The  line  of  demarcation  between  the  two 
portions  is  abrupt  and  dentated.  The  right  portion,  the  villous,. 
or  true  digestive  coat,  is  reddish  in  colour,  soft,  very  vascular, 
and  velvety-looking.  When  examined  with  a  lens,  it  appears 
honey-combed,  or  covered  by  small  shallow  polygonal  depressions 
or   alveoli,   separated  from  each   other   by  projecting  intervals. 


Internal  aspect  of  Horse's  stomach,  opened  from  below,  a  a,  Cuticular  mucous 
membrane  ;  i  6,  Villous  mucous  membrane  ;  c  c  c,  Line  of  demarcation  between 
the  two  portions  ;  d,  Cardiac  orifice  ;  e.  Pyloric  orifice  and  valve. 

Into  these  alveoli  the  gastric  follicles  open ;  the  latter  lie  in  the 
subepithelial  tissue,  perpendicular  to  the  surface  of  the  mem- 
brane ;  at  the  pyloric  end  some  of  these  folliqles  terminate  in 
dilated  sacs,  or  divide  into  two  or  more  tubes.  They  consist  of 
a  basement  membrane,  lined  by  columnar  epithelium  ;  some  of 
them  secrete  gastric  juice,  others  mucus  ;  the  latter  are  lined 
throughout  with  epithelium,  while  the  gastric  juice  follicles  have 
their  lower  part  filled  with  nucleated  cells  and  granules.  The 
villous  coat  is  also  covered  with  numerous  simple  or  lenticular 
follicles. 

The  mucous  membrane,  when  the  organ  is  empty,  is  thrown 
into  folds,  or  rugce,  which  are  very  well  seen  in  the  villous  por- 


304  SPLANCHNOLOGY, 

tion,  where  they  do  not  entirely  disappear  on  inflation.  The 
cardiac  orifice  is  closed  by  the  mucous  membrane  of  the  03S0- 
phagus  ;  its  numerous  folds  completely  filling  that  tube  at  its 
termination  when  empty  ;  the  valve  thus  formed  is  air-tight. 

The  arteries  of  the  stomach  arise  from  all  the  branches  of  the 
coeliac  axis  ;  they  are  the  gastric,  the  left  gastro- epiploic  from 
the  splenic,  and  the  right  gastro-epiploic  from  the  hepatic  ;  the 
"blood  is  returned  by  satellite  veins  which  join  the  vena  porta. 
The  nerves  are  from  the  pneumogastric,  and  solar  plexus  of  the 
sympathetic. 

The  use  of  the  stomach  is  to  macerate  the  food  by  the  action 
of  its  muscular  walls,  and  also  to  saturate  it  with  mucus  and 
gastric  juice,  the  latter  containing  a  principle  called  pepsine, 
which  acts  chemically  on  albuminous  mattcis.  The  entire 
operation  is  called  cliymification,  and  the  food  thus  prepared  the 
chyme. 

THE   INTESTINES. 

These  are  divided  into  the  large  and  small ;  the  two  however 
form  a  continuous  musculo-membranous  tube,  the  small  intestine 
being  likewise  continuous  with  the  stomach  at.  its  pyloric  orifice. 
These  organs  are  tortuous  in  their  course,  and  in  herbivorous 
animals  are  long  and  capacious. 


SMALL    INTESTINE. 

The  small  intestine  commences  at  the  pylorus,  and  terminates, 
in  the  caecum.  It  consists  of  a  cylindrical  convoluted  tube,  rather 
more  than  an  inch  in  diameter,  and  about  seventy-two  feet  in 
length.  It  presents  two  curvatures-,  the  greater  one,  convex  and 
free,  the  lesser  concave  and  attached  to  the  mesentery,  by  which 
it  is  suspended  from  the  roof  of  the  abdomen,  occupying  the 
central  region,  and  partly  surrounded  by  the  large  intestine.  It 
is  arbitrarily  divided  into  the  Duodenum,  the  Jejunum,  and  the 
Ileum. 

The  duodenum,  continuous  with  the  pylorus,  is  the  only  fixed 
portion  of  the  small  intestine.  In  the  horse  it  is  short,  present- 
ing a  dilatation  at  its  origin  resembling  a  miniature  stomach, 
with  its  curvatures  disposed  inversely  to  those  of  the  stomach 
itself.  On  leaving  the  pylorus  it  runs  forwards,  then  backwards, 
forming  an  abrupt  curve.      It  now  crosses  from  right  to  left,  and 


SMALL    INTESTINE. 


305 


becomes  the  jejunum  at  the  level  of  the  anterior  mesenteric 
artery.  The  first  portion  is  more  free  than  the  latter.  At  from 
four  to  five  inches  from  the  pylorus  is  the  opening  by  which  the 
ducts  of  the  liver  and  the  pancreas  enter  the  intestine.  The. 
jejunum  succeeds  the  duodenum,  and  includes  about  two-fifths  of 
the  remainder  of  the  small  intestine,  the  ileum  constituting  the 
rest  ;  both  are  floating — i.e.,  they  are  attached  to  the  free  edge 
of  the  mesentery.  The  ileum  terminates,  in  the  right  iliac  region, 
in  the  large  intestine. 


Fio   100. 
The  two  mesenteries ;  the  great  colon  being  removed,    a,  Anterior  mesentery  ;  h  h.  Mesenteric 
glands;  c  c  c,  Loops  of  the  small  intestine  ;  d.  Colic  mesentery  ;  e  e  c.  Loops  of  the  floating  colon  : 
/,  Sphincter  ani— internal  layer  ;  g,  Levator  ani. 

The  walls  of  the  small  intestine,  in  common  with  all- hollow 
viscera  of  the  abdomen,  consist  of  an  external  serous,  a  middle 
muscular,  and  an  internal  mucous  coat.  The  two  latter  are 
joined  by  areolar  tissue,  which  is  sometimes  regarded  as  a 
submucous  coat.  The  serous  coat  envelops  the  intestine,  except- 
ing just  at  its  attached  border,  where  the  two  folds  join  and  form 
the  mesentery.  The  muscular  coat  consists  of  two  layers  of 
fibres,  an  outer  longitudinal,  which  is  very  thin,  especially  at  the 
attached  border,  and  an  inner  circular  one,  which  is  thicker ;  both 
are  pale,  and  involuntary. 

The  mucous  coat  is  soft,  spongy,  reddish,  and  vascular,  covered 

X 


306 


SPLANCHNOLOGY. 


by  nuQierous  minute  villi  and  follicular  openings,  the  whole 
being  clothed  by  columnar  epithelium.  It  is  thrown  into  folds 
when  empty,  which  usually  disappear  when  it  is  dilated  ;  these 
.are  known  as  valvulce  conniventes. 


INTESTINAL    GLANDS. 

The  mucous  membrane  of  the  small  intestine  is  furnished  with 
glands  and  absorbents.  Besides  the  mucous  follicles,  we  note  the 
following  glands  : — 

Glands  of  Brunner.  I  Payer's  patches. 

Crypts  of  Lieberkiihn.  j  Solitary  glands. 

The  glands  of  Brunner,  which  are  small  glands,  resembling 
the  acini  of  the  salivary  glands,  are  found  in  the  duodenum. 

The  crypts,  or  follicles  of  Lieberkuhn,  are  very  small,  and  are 
found  throughout  the  intestines,  between  the  villi  and  around  the 
larger  glands. 

The  glands  or  patches  of  Ftyer,  are  oval  or  circular  groups  of 
solitary  glands,  forming  agminated  glands,  and  are  found  in  the 
jejunum  and  ileum  ;  they  are  mOst 
numerous  near  the  termination  of  the 
ileum.  Each  gland  is  a  simple  vesi- 
cular ductless  sac,  containing  a  lym- 
phoid material.  Single  sacs,  similar 
to  those  forming  Peyer's  patches, 
called  solitary  glands,  are  scattered 
throughout  the  intestines,  and  sur- 
rounded by  LieberkUhn's  crypts, 
which  form  round  each  gland  a  ring 
known  as  the  corona  tubulorum. 

The  absorbents  originate  in  the 
villi,  which  are  small,  finger-like, 
vascular  processes,  thickly  distri- 
buted over  the  mucous  surface ; 
they  consist  of  loops  of  the  lacteal 
or  chyle  vessels,  surrounded  by  a 
net-work  of  capillaries,  fine  muscular  fibres,  and  small  gran- 
ular corpuscles,  with  a  mucous  layer  covered  by  columnar 
epithelium.  The  small  intestines  are  supplied  with  blood 
by  the  anterior  mesenteric  and  duodenal  branch  of  the  hepatic 
arteries,    the    blood    being    returned   by    the  satellite    veins    to 


ITlo.  101. 

"Section  of  mucous  membrane  of  the  small 
Intestine.  Ou  the  left  a  villus  is  seen  in 
section,  a,  The  epithelial  covering ;  c,  The 
blood-vessels ;  d,  The  basement  membrane, 
or  subepithelial  layer ;  e,  Spaces  for  re- 
ception of  the  chyle  ;/,  Origin  of  a  lacteal 
vessel.  On  the  right  is  a  follicular  depres- 
sion in  the  mucous  membrane,  with  b.  The 
cells  lining  it ;  and  c.  The  subepithelial 
layer. 


c^cuM.  307 

the  portal  system.  The  lymphatic  vessels  of  the  small  intes- 
tine are  distinctively  known  as  the  lacteal  vessels,  and  they 
convey  away  the  chyle  absorbed  by  the  medium  of  the  villi.  The 
nerves  are  from  the  solar  plexus.  The  vessels  and  nerves  gain 
or  leave  the  small  intestine  by  passing  between  the  two  folds  of 
peritoneum  which  form  the  mesentery. 

In  the  duodenum  the  chyme  becomes  saturated  with  the  bile 
and  pancreatic  juice,  the  change  thus  induced  being  termed 
chylification  or  conversion  of  the  chyme  into  chyle.  In  the  rest 
of  the  intestine  we  note  the  absorption  of  the  chyle  by  the  lacteals, 
the  final  preparation  of  the  food  by  the  various  gland  secretions, 
and  the  reabsorption  of  the  bile  by  the  blood-vessels.  Chyle  is  a 
milky-looking  fluid,  its  turbidity  being  due  to  the  presence  of  an 
immense  number  of  minute  granules.      It  contains  also  the  chyle 


Fia.  102. 
A,  Microscopic  appearance  of  a  drop  of  chyle  from  the 
thoracic  duct ;   a,  Granular  base ;  6,  Fatty  particles ;  e. 
Chyle  corpuscles  ;  B,  Isolated  corpuscles  showing  the  cell- 
membrane  in  its  developing  stages,  abed. 

corpuscles,    which   are    nucleated   sacs   resembling    those    of  the 
lymph,  or  the  colourless  corpuscles  of  the  blood. 


LARGE  INTESTINE. 

The  large  intestine  extends  from  the  termination  of  the  ileum 
to  the  anus,  and  may  be  regarded  as  consisting  of  four  parts, 
which  will  be  described  in  order:  the  Caecum,  the  Great  colon, 
the  Floating  colon,  and  the  Rectum. 


C^CUM. 

The  caecum,  blind  intestine,  or  caput  ccecum  coli,  is  a  large 
cul-de-sac,  commencing  in  the  right  iliac  region,  passing  obliquely 
downwards  and  forwards,  and  terminating  in  the  left  hypochon- 
driac   region    by  a    pointed,    blind   extremity ;    thus   it   crosses 


308  SPLANCHNOLOGY. 

obliquely  the  middle  line  of  the  abdominal  floor.  It  measures- 
about  thirty-six  inches  in  length,  and  its  capacity  may  average  six 
gallons.  It  is  somewhat  conical  in  shape,  and  curved  at  its  supero- 
posterior  extremity,  presenting  on  its  outer  surface  a  number  of 
circular  constrictions,  and  certain  longitudinal  muscular  bands,  of 
which  there  are  four  about  the  middle.  The  superior  extremity  is 
called  the  base  or  arch,  and  presents  a  convex  curvature  directed 
backward,  and  a  concave  one  forwards.  In  the  concave  curvature 
the  ileum  terminates,  and  there  also  the  large  colon  originates. 
The  middle  part  of  the  caecum  is  related  with  the  small  intes- 
tines, the  apex  being  free,  and  prolonged  to  the  sternum.  It  is 
fixed  to  the  abdominal  wall  posteriorly  by  cellular  tissue,  and  to 
the  origin  of  the  colon  by  a  double  fold  of  peritoneum,  called  the 
meso-caecum. 

The  interior  of  the  caecum  presents  a  number  of  transverse 
ridges,  corresponding  to  the  external  transverse  constrictions.  Two 
orifices,  placed  one  above  the  other,  are  found  in  its  concave 
curvature;  the  inferior  one  marks  the  termination  of  the  ileum, 
and  is  guarded  by  the  ileo-coecal  valve,  which  is  formed  by  a 
doubling  of  the  mucous  membrane,  within  which  is  a  band  of 
muscular  fibres.  The  superior  opening  communicates  with  the 
colon.  The  caecum  has  three  coats,  serous,  muscular,  and  mucous, 
the  latter  being  thicker  than  that  of  the  small  intestines,  and 
having  neither  Brunner's  glands  nor  Peyer's  patches.  The  folli- 
cles of  Lieberkiihn,  solitary  glands,  and  a  few  scattered  villi  are 
however  present. 

GREAT    COLON. 

The  great  or  double  colon  originates  from  the  caecum,  and  ter- 
minates near  its  origin  in  an  abrupt  contraction,  whence  arises 
the  floating  colon.  Taken  out  of  the  abdomen,  it  appears  as  a 
voluminous  tube,  with  successive  dilated  and  constricted  portions; 
like  the  caecum,  it  is  marked  throughout  by  longitudinal  bands 
and  transverse  furrows.  It  measures,  on  an  average,  from  nine  to 
eleven  feet  in  length,  and  sometimes  has  the  capacity  of  eighteen 
gallons.  It  is  doubled  on  itself,  forming  two  branches  of  equal 
length,  placed  one  on  the  other,  and  so  disposed  that  the  terminal 
end  is  near  the  origin.  When  in  situ,  the  doubled  portion 
forms  a  curve  whose  convexity  is  directed  forwards,  and  corre- 
sponds to  the  walls  of  the  abdomen,  thus  forming  four  divisions, 
a  right  and  left  being  above,  and  a  right  and  left  below,  with 


GREAT    COLON. 


30& 


three  Jiexiiycs  or  oends.  la  tracing  its  course,  these  tour  divisions 
present  themsshes  thus.  Leaving  the  arch  of  the  caecuna  in  the 
right  lumbar  region,  it  passes  obliquely  forwards  to  the  posterior 
surface  of  the  diaphragm  in  the  epigastric  region,  where  it  turns 
round  to  the  left,  forming  the  first  or  sternal  flexure.  Here  the 
second   division  originates,  and  in  contact  with  the  inferior  ab- 


f  IG.  103. 
i,^.Csecum  ;  h, 


CiEcura  and  Great  Colon  of  a  Horse.  a,!.Caecum  ;  &,  c,  Its  muscular  bands  ;  d.  Termination  of  the 
ileum;  e.  First,  c',  Second,  /,  Third,  and  /',  Fourth  division  of  colon  ;  g,  Pelvic  flexure ;  h,  Ongln 
of  Floating  Colon.     The  arrows  indicate  the  course  of  the  food  through  the  colon. 

<lominal  walls,  it  runs  backwards  to  the  hypogastric  region,  where 
it  is  doubled  upon  itself,  forming  the  second,  sigmoid  or  pelvic 
flexure.  From  this  flexure,  the  third  portion  passes  forwards, 
above  and  to  the  left  of  the  second,  to  which  it  is  attached  by 
cellular  tissue  and  peritoneum,  reaches  the  diaphragm,  and  is 
inflected  upwards  to  the  right,  forming  the  third  or  diaphrag- 
matic flexure,  which  is  in  relation  with  and  below  the  liver  and 


310  SPLANCHNOLOGY. 

stomach.  From  this  flexure  proceeds  the  fourth  and  last  part  of 
the  large  colon,  which  passes  backwards,  and,  at  the  level  of  the 
base  of  the  csecum,  is  constricted,  and  continued  as  the  floating 
colon. 

The  attachments  of  the  large  colon  are,  at  its  origin,  to  the 
cascum  by  the  meso-csecum,  at  its  terminal  portion  by  cellular 
tissue  to  the  pancreas  and  arch  of  the  csecum,  and  by  the  meso- 
colon, a  double  fold  of  peritoneum  which  unites  the  two  halves 
for  some  distance,  enveloping  the  entire  organ  except  at  its 
junction  with  other  viscera,  and  attaching  it  to  the  sublumbar 
portion  of  the  abdominal  wall.  The  diameter  of  the  canal  varies. 
Very  narrow  at  its  origin,  it  abruptly  enlarges,  and  its  size  then 
remains  much  the  same  as  far  as  the  pelvic  flexure,  where  it 
contracts  ;  the  third  division  is  comparatively  small,  but  at  the 
third  flexure  it  again  expands,  the  fourth  division  being  the 
largest  of  all  ;  it  is  finally  constricted,  as  it  forms  the  origin  of 
the  floating  colon.  Externally,  it  has  numerous  transverse  furrows 
and  longitudinal  muscular  bands ;  the  latter  vary  in  number ;  as 
far  as  the  pelvic  flexure,  there  are  four ;  along  the  narrow  third 
portion,  only  one ;  at  the  third  flexure,  again  three,  which  persist, 
two  being  continued  along  the  floating  colon.  The  internal 
surface  resembles  that  of  the  csecum. 

FLOATING   COLON. 

The  single  or  floating  colon  succeeds  the  great  colon,  and  is 
convoluted,  like  the  small  intestines,  but  is  twice  as  large,  in 
length  averaging  about  ten  feet,  and  regularly  crumpled  by  trans- 
verse folds  and  longitudinal  muscular  bands.  The  latter  are  two 
in  number,  one  on  the  greater  or  convex,  the  other  on  the  lesser 
or  concave  curvature.  It  leaves  the  large  colon  to  the  left  of  the 
caecum,  in  close  relation  with  the  termination  of  the  duodenum. 
It  principally  occupies  the  left  flank  or  lumbar  region,  its  con- 
volutions mixing  with  those  of  the  small  intestine,  and  near  the 
anterior  part  of  the  pelvis  it  terminates  in  the  rectum.  Floating 
like  the  small  intestine,  it  is  suspended  by  the  colic  mesentery, 
which  is  larger  than,  but  resembles  in  structure  that  of,  the  small 
intestine. 

RECTUM. 
The  rectum,  or  straight  intestine,  extends  in  a  direct  line  from 
the  entrance  of  the  pelvic  cavity  to  the  anus,  and  resembles  in 


ANUS.  311 

structure  the  floating  colon,  but  its  walls  are  thicker,  and  more 
dilatable.  It  is  related  superiorly  with  the  sacrum ;  inferiorly 
with  the  bladder,  vasa  deferentia,  vesiculae  seminales,  Cowper's 
glands,  and  the  prostate  gland  in  the  horse  ;  in  the  mare,  with 
the  vagina  and  uterus  ;  laterally  it  is  related  with  the  walls 
of  the  pelvic  cavity.  It  is  attached  to  a  continuation  of  the  colic 
mesentery,  called  the  meso-redum  ;  to  the  pelvis  'by  a  reflection 
of  peritoneum  ;  and  to  the  sacrum  by  the  suspensory  ligaments 
of  the  penis,  which,  uniting  below,  at  the  posterior  extremity, 
surround  it;  finally,  by  two  triangular  fasciculi  of  pale  muscular 
fibres,  which  pass  up  above  the  anus,  and  are  inserted  to  the 
inferior  surface  of  the  coccyx,  between  its  depressor  muscles. 
The  serous  coat  is  a  reflection  of  the  peritoneum  ;  the  muscular 
is  very  strong,  consisting  of  longitudinal  bands,  with  circular 
fibres  beneath  them.  The  mucous  coat  is  similar  to  that  of  the 
colon;  its  surface  presents  a  number  of  transverse  ridges,  similar 
to  thoso  of  the  caecum  and  large  colon.  In  the  spaces  between 
these  ridges,  the  faeces  assume  their  characteristic  shape. 

ANUS. 

The  anus  is  the  posterior  opening  of  the  alimentary  ca,na\. 
Lying  below  the  root  of  the  tail,  it  forms  a  round  projection, 
which  becomes  less  prominent  with  age.  It  consists  of  thin, 
hairless  skin  externall}',  and  of  mucous  membrane  internally,  the 
two  being  continuous.  In  the  fold  between  them  are  the  muscles, 
the  terminal  muscular  fibres  of  the  rectum,  and  a  certain  quantity 
of  fat. 

The  muscles  connected  with  the  anus  are — 

Sphincter  Ani.  |  Levator  -Ani. 

Retractor  Ani. 

SPHINCTER  ANI. 

(Fig.  100./.) 

Situated  round  the  termination  of  the  rectum,  this  muscle  is 
•circular,  with  a  central  opening,  some  of  the  fibres  blending  with 
the  muscles  of  the  perineal  region.  It  is  attached  to  the  fascia 
covering  the  perineum,  and  to  tke  coccygeal  vertebrae,  and  con- 
sists of  two  layers.  The  inner  layer  is  pale,  being  part  of  tho 
muscular  coat  of  the  rectum. 

Action. — To  close  the  anus. 


312 


SPLANCHNOLOGY. 


LEVATOR    ANI. 
(Fio.  100.  g.) 

This  name  has  been  applied  to  a  kind  of  small  muscular  liga- 
ment which  joins  the  rectum  to  the  coccyx  above. 

RETRACTOH   ANI. 

Situated  on  the  side  of  the  anus,  this  is  a  broad,  flat,  and 
powerful  muscle,  arising  from  a  rough  margin  just  behind  the 
acetabulum,  and  the  inner  surface  of  the  sacro-sciatic  ligament. 
It  is  inserted  to  the  lateral  aspect  of  the  anus,  its  fibres  blend- 
ing with  the  sphincter. 

Action. — To  retract  the  anus. 

The  anterior  mesenteric  artery  supplies  the  csecum  and  great 
colon,  the  posterior  mesenteric  artery  supplying  the  rest  of  the 
large  intestine,  assisted  by  the  internal  pudic.  The  blood  is 
returned  by  the  mesenteric  veins  to  the  portal  vein.  The  nerves 
come  from  the  mesenteric  and  hypogastric  plexuses. 

The  csecum  seems  to  be  a  reservoir  for  the  large  quantities  of 
fluid  swallowed  by  the  animal.  In  it  and  in  the  great  colon 
absorption  of  fluid  takes  place,  but  the  bulk  of  the  ingesta 
which  are  passed  into  the  floating  colon  consists  of  residual  or 
faecal  matter,  having  been  deprived  of  its  nutritive  principles. 
HeUce  the  floating  colon  may  be  regarded  as  being  partly,  the 
rectum  entirely,  an  excretory  organ. 

Accessory  Organs  of  Digestion. 

In  the  abdominal  region  these  organs  are  the  Liver,  the 
Pancreas,  and  the  Spleen. 

liver. 

The  liver  is  a  solid  gland,  situated  in  the  abdomen,  extending 
from  the  right,  through  the  epigastric,  to  the  left  hypochondriac 
region.  It  is  the  largest  secreting  gland  in  the  body,  weighing 
from  ten  to  twelve  pounds,  and  in  shape  is  very  irregularly 
elliptical,  thick  in  the  centre,  gradually  thinning  at  the  borders, 
and  presenting  numerous  clefts ;  it  has  two  surfaces  and  a  cir- 
cumference. The  anterior  surface  is  smooth,  convex,  and  cleft 
by  a  deep  vertical  fissure,  in  which  lies  the  posterior  vena  cava 


LIVER.  '  313 

the  latter  before  it  penetrates  the  diaphragm,  receiving  the 
hepatic  veins.  The  posterior  surface  is  smooth,  convex,  and 
marked  superiorly  with  the  large  transverse  fissure  by  which 
the  vena  porta,  hepatic  artery,  and  nerves  enter,  and  the  hepatic 
canals  leave  the  liver.  Being  suspended  from  the  diaphragm  in 
a  direction  sloping  downwards  from  right  to  left,  the  circum- 
ference may  be  divided  into  a  superior  right  and  an  inferior  left. 
The  superior  border  presents,  from  right  to  left,  the  attachment 
of  the  ligament  of  the  right  lobe.      The  inferior  border  is  cleft  by 


Fig.  104. 
Posterior  view  of  the  liver  and  diaphragm  in  situ,  a,  Left  lobe ;  b,  Right 
lobe ;  c.  Quadrate  lobe ;  d,  Spigelian  lobe  ;  d'.  Spigelian  ligament ;  just  above 
is  the  right  kidney ;  e.  Left  lateral  ligament ;  /,  Right  lateral  ligament ;  g, 
Broad  ligament ;  h,  Hepatic  duct ;  i,  Piece  of  the  duodenum  opened  to  show, 
k,  Opening  of  the  ductus  pancreaticus  minor,  and  I,  Eminence  of  Vater ; 
III,  Vena  porta;  n,  Posterior  vena  cava  ;  o,  Notch  for  the  cesophagus. 

two  fissures,  which  divide  the  organ  into  three  lobes  ;  a  right, 
superior,  a  middle,  and  a  left  inferior.  The  right  lobe,  the  largest, 
is  flattened,  and  semi-ovoid,  with  the  point  downwards  ;  it  has 
on  the  upper  part  of  its  posterior  surface  a  secondary  pyramidal 
lobe,  the  lohulus  Spigelii,  to  the  left  of  which  a  slight  projection 
of  the  right  lobe  is  sometimes  called  the  lohulus  caudatus.     The 


314)  SPLANCHNOLOGY. 

middle  lobe,  the  smallest,  is  placed  below  the  transverse  fissure, 
and  consists  of  several  small  lobes  formed  by  clefts  in  its  inferior 
border ;  sometimes,  from  its  square  shape,  it  is  called  the  lohulus 
quadratus.  The  middle  lobe  of  the  liver  is  related  with  the 
centre  and  inferior  portions  of  the  diaphragm.  The  left  lobe 
resembles  generally  the  right  in  form,  but  is  rather  smaller, 
situated  lower  down,  and  in  the  left  hypochondriac  region. 

The  ligaments  of  the  liver  are  six  in  number,  five  being  parti}- 
formed  by  the  peritoneum,  while  thfe  sixth  is  the  round  ligament, 
or  fibrous  remains  of  the  umbilical  vein,  a  foetal  structure,  which, 
ascending  from  the  umbilicus  to  the  anterior  fissure,  is  embedded 
in  the  folds  of  the  broad  ligament. 

The  broad  or  suspensor-y  ligament  consists  of  two  adherent 
layers  of  peritoneum,  one  border  being  attached  to  the  anterior 
surface  of  the  middle  lobe,  the  other  to  the  posterior  surface  of 
the  diaphragm  and  abdominal  floor ;  the  round  ligament  is 
situated  between  these  folds. 

The  coronary  ligament  consists  of  fibres  covered  by  peri- 
toneum, and  passes  from  the  superior  border  of  the  anterior  fissure 
to  the  pillars  of  the  diaphragm,  being  attached  to  the  posterior 
vena  cava. 

The  Qnght  lateral  ligament,  in  common  with  the  coronary  and 
left  lateral,  consists  of  a  double  layer  of  peritoneum,  strengthened 
by  white  fibrous  tissue  ;  it  stretches  from  the  superior  border  of 
the  right  lobe  and  lobulus  Spigelii  to  the  diaphragm. 

The  left  lateral  ligament  passes  from  the  upper  border  of  the 
left  lobe  of  the  liver  to  the  left  side  of  the  foramen  sinistrum  of 
the  diaphragm,  being  attached  to  the  fibrous  phrenic  centre.  In 
addition  to  the  above,  there  is  a  small  double  fold  of  peritoneum 
joining  the  upper  border  of  the  lobulus  Spigelii  to  the  right 
kidney  ;  it  has  been  named  the  Spigelian  ligament. 


STRUCTURE  OF   THE   LIVER. 

The  coverings  of  the  liver  are  an  external  serous,  and  an 
internal  fibrous  coat. 

The  serous  coat  of  the  liver  is  a  part  of  the  peritoneum,  and 
is  reflected  from  the  surface  of  the  gland  to  assist  in  forming  the 
ligaments  and  gastro-hepatic  omentum.  The  inner  coat  consists 
of  a  thin  fibrous  membrane,  adherent  to  the  serous  coat  and  to 
the  glandular  substance.     It  invests  the  entire  organ,  and  passes. 


LIVER.  315 

into  the  several  openings  in  the  posterior  or  transverse  fissure ; 
numerous  plates  from  it  penetrate  the  substance  of  the  gland, 
and  separate  the  ultimate  hepatic  lobules.  This  inflected  sheath 
is  named  Glisson's  capsule,  and  processes  from  it  line  the  portal 
canals,  which  pierce  the  substance  of  the  liver,  and  envelop  the 
branches  of  the  portal  vein,  the  hepatic  artery,  and  biliary  ducts, 
which  run  in  these  canals.  It  thus  forms  a  web  in  which  these 
vessels  ramify,  and  surrounds  the  lobules,  binding  them  together. 
It  is  divided  into  two  portions ;  the  vaginal,  loose  and  abundant, 
lining  the  portal  canals ;  and  the  interlobular,  which  forms  the 
capsules  of  the  lobules,  and  supports  the  ramifications  of  the 
smaller  vessels. 

The  hepatic  substance  is  variable  in  colour,  depending  upon 
the  quantity  and  quality  of  the  blood  and  bile  in  its  vessels.  Its 
normal  colour  is  a  cool  brown ;  in  an  animal  that  has  died  from 
haemorrhage  it  is  a  bleached  yellowish  grey ;  from  general  con- 
gestion, a  purplish-brown  or  chocolate ;  from  obstruction  of  the 
biliary  ducts,  yellow.  It  is  easily  lacerated,  the  rupture  being 
granulated.  It  consists  of  very  minute  lobules,  varying  from  about 
jJ^  to  -jJg-  of  an  inch  in  diameter,  separated  from  each  other 
by  the  interlobular  tissue,  continuous  with  Glisson's  capsule. 
A  lobule  is  divided  externally  into  a  base,  and  capsular  surface 
or  periphery.  The  base  is  polygonal  and  flat,  resting  upon  a. 
small  branch  of  the  hepatic  vein — the  sublobular  ;  joining  which, 
and  piercing  the  centre  of  the  lobule,  is  the  intralobular  vein. 
The  periphery  or  capsular  surface  is  developed  into  blunt  pro- 
cesses, giving  the  lobule,  which  cut  longitudinally,  a  foliated 
appearance.  The  surfaces  are  imperfectly  isolated  from  the 
surrounding  lobules  by  a  thin  layer  6f  Glisson's  capsule  and  by 
the  smaller  vessels,  the  intervals  being  the  interlobular  spaces. 
Each  lobule  consists  of  numerous  cells,  biliary  ductlets,  a  plexus  of 
capillary  blood-vessels,  and  probably  minute  nerves  and  absorbents. 
Hepatic  cells  form  the  bulk  of  each  lobule,  and  are  irregularly 
polygonal  in  shape,  averaging  about  -^^  of  an  inch  in  diameter, 
and  containing  a  nucleus,  nucleolus,  granular  matter,  and  particles 
of  fat.  They  are  arranged  in  rows,  radiating  from  the  centre  of 
the  lobule,  and  lie  in  the  interspaces  of  the  vascular  plexuses. 

The  liver  is  supplied  with  nutritive  blood  by  the  hepatic  artery, 
a  branch  of  the  coeliac  axis ;  with  functional  blood  by  the  portal 
vein,  both  kinds  of  blood  being  returned  by  the  hepatic  veins. 

The  portal  vein  enters  the  liver  at  the  transverse  fissure. 


316 


SPLANCHNOLOGY. 


accompanied  by  the  hepatic  artery  and  duct,  all  being  invested 
by  Glisson's  capsule ;  it  is  divided,  into  right  and  left,  and  each 
part  subdivides  in  the  portal  canals  until  it  reaches  the  inter- 
lobular spaces,  where  it  gives  off  the  interlobular  branches. 
These  ramify  in  the  interlobular  spaces,  on  the  capsules  of  the 
lobules,  where  they  give  off  lobular  branches,  that  penetrate  the 
lobules,  forming  in  each  an  intralobular  ^dexus,  which  terminates 
in  an  intralobular  branch  of  the  hepatic  vein. 

The  hepatic  artery  enters  the  liver  at  the  transverse  fissure,  in 
company  with  the  portal  vein  and  biliary  duct.  With  them  it 
ramifies  in  the    portal    canals,  giving  off    vaginal  branches  to 

Glisson's  capsule,  and  to  the 
coats  of  the  portal  vein  and 
biliary  duct  ;  interlobular 
branches,  which  pass  to  the 
capsules  of  the  lobules,  ter- 
minating in  the  capillary 
plexus  within  them  ;  and  cap- 
sular branches  which  chiefly 
supply  the  capsule  of  the 
liver.  The  following  names 
have  also  been  applied  to 
these  vessels  : — ^Rami  Vascu- 
lares,  supplying  the  walls  of  bile 
ducts  and  blood  vessels,  as  Vasa 
Vasorum ;  Rami  Capsulares, 
supplying  the  capsule ;  and 
Rami  Lobulares  supplying  the 
substance  of  the  lobule. 
The  hepatic  vein  commences  in  the  interior  of  each  lobule  by 
twiglets  which  converge  to  form  the  intralobular  vein,  which 
leaves  the  lobule  at  the  middle  of  its  base,  and  enters  the  sub- 
lobular  vein.  The  sublobular  veins  unite  to  form  large  and  still 
larger  veins,  the  hepatic  veins,  which  finally  join  the  vena  cava 
in  the  anterior  fissure. 

The  hepatic  or  bile  duct  is  the  duct  of  the  gland,  conveying 
away  its  secretion,  the  bile. 

The  biliary  tubes  originate  within  the  lobules  in  a  plexus 
among  the  hepatic  cells,  called  the  intralobular  biliary  plexus, 
which  on  the  capsule  of  the  lobule  forms  the  interlobular 
branches,  which  join  each  other,  gain  the  portal  canals,  and  ulti- 


FlO.  105. 

Horizontal  section  of  three  hepatic  lobules. 
<i  a.  Intralobular  veins — origins  of  the  hepatic 
system ;  6  h,  Interlobular  veins— terminations  of 
the  portal  system.  The  capillaries  joining  the 
two  systems  are  the  intralobixlar  plexuses. 


LIVER.  3  1 7 

mately  unite  to  form  the  hepatic  duct,  which  leaves  the  liver  at 
the  transverse  fissure. 

It  is  believed  by  some  of  the  best  authorities  that  the  so-called 
intralobular  bile  tubes  or  capillaries  are  mostly  mere  spaces 
between  the  cells,  the  tubes  being  formed  only  at  the  periphery 
of  the  lobule. 

The  hepatic  or  bile  duct  (ductus  choledochus)  thus  results 
from  the  union  of  the  branches  of  the  hepatic  tubes  in  the  pos- 
terior fissure  of  the  liver.  On  leaving  the  liver,  it  passes  between 
the  folds  of  the  gastro-hepatic  omentum,  and  reaches  the  walls  of 
the  duodenum,  where  it  meets  with  the  principal  duct  from  the 
pancreas  ;  both  these  ducts,  in  the  horse,  enter  tlie  duodenum 
together,  some  five  inches 
from  the  pylorus.  In  some 
cases  the  two  ducts  have 
been  found  to  unite  before 
reaching  the  wall  of  the 
duodenum,  thus  forming  a 
short,   single  canal,  termed  fig.  loe. 

the  ductus  communis.     The  section  showing  the  manner  in  which  the  Bile  and 

^-^^■r.:^^    :^      ~    „    J^J      l^„     ^  Pancreatic  Ducts  enter  the  Intestine,     a.   Duct  of 

opening     is     guarded     by     a  wirsung ;    6,  Bile  duct ;    c,  union  of  the  two  ducts 

prominent     circular    fold    of  on  the  eminence  of  Vater :  d,   Valve ;   e,  Muscular 

,                  ,               .  coat  of  duodenum  ;  /,  mucous  coat  of  ditto. 

raucous  membrane,  the  emi- 
nence of  Vater,  which  serves  as  a  valve,  preventing  the  entrance 
of  food  from  the  duodenum.  The  ductus  choledochus  and  larger 
bile  tubes  consist  of  an  external  fibrous  and  slightly  muscular 
coat,  and  an  internal  mucous  coat,  lined  with  columnar  epithelium, 
and  studded  with  numerous  glands. 

The  nerves  come  from  the  solar  plexus,  with  branches  from  the 
pneumogastric  and  diaphragmatic  nerves. 

The  blood  of  the  portal  vein,  returned  chiefly  from  the 
abdominal  alimentary  canal,  is  charged  with  bile,  which  it  is  the 
principal  function  of  the  liver  to  remove.  This  is  achieved  by 
the  vital  power  of  the  hepatic  cells,  while  the  blood  is  passing 
through  the  intralobular  capillaries.  The  blood  thus  deprived  of 
bile,  passes  into  the  intralobular  veins,  and  so  into  the  sublobular 
and  hepatic  veins,  while  the  bile  gains  the  bile  tjibes,  and  ulti- 
mately the  hepatic  duct,  to  be  poured  again  into  the  intestine. 
Bile  is  a  greenish-yellow,  viscid  fluid,  with  an  alkaline  reaction ; 
it  is  believed  to  stimulate  peristaltic  action,  and  the  secretions . 
of  the  oflands  in  the  mucous  membrane. 


318 


SPLANCHNOLOGY. 


In  solipedes,  also  in  the  elephant  and  hyrax,  the  secretion  of 
bile,  although  more  active  during  digestion,  is  constant,  there 
being  no  reservoir  for  it.  Most  animals  are  however  provided 
with  a  gall  bladder,  lodged  in  a  fissure  on  the  posterior  surface 
of  the  gland,  in  which  the  bile  accumulates  during  the  period  of 
abstinence,  and  from  which  it  passes  into  the  intestinal  canal 
when  digestion  commences. 


PANCREAS. 

The  pancreas  is  a  compound  conglomerate  gland,  and  resembles, 
the  salivary  glands  in  structure  and  physical  properties,  but  it  is 
looser  and  softer,  and  of  a  reddish-cream  colour.  It  is  situated 
behind  the  stomach  and  liver,  and 
in  front  of  the  kidneys,  related  with 
the  posterior  aorta,  posterior  vena 
cava,  and  pillars  of  the  diaphragm, 
to  which  it  is  slightly  attached  by 
connective  tissue. 

Its  sha.pe  in  the  horse  is  very 
irregular  and  variable,  but  it  is 
slightly  curved  upon  itself,  flattened 
from  above  downwards,  and  presents 
a  right,  a  left,  and  an  inferior  branch. 
An  oblique  opening,  the  ring  of  the 
pancreas,  passes  from  the  inferior 
to  the  superior  surface,  through 
which  the  vena  porta  "runs,  in  its 
passage  to  the  liver,  and  imme- 
diately above,  on  the  superior  border, 
is  a  notch  for  the  great  mesenteric 
artery.  The  surfaces  are  flat  and 
lobulated  ;  the  superior  one  -  is 
partly  covered  by  peritoneum  and  attached  by  cellular  tissue  to 
the  aorta,  coeliac  axis,  posterior  cava,  and  right  kidney.  The 
inferior  surface  is  attached  to  the  base  of  the  caecum  and  terminal 
portion  of  the  double  colon  by  cellular  tissue.  The  anterior 
border  contacts  the  duodenum  and  left  cul-de-sac  of  the  stomach. 
The  posterior  is  convex;  about  the  centre  is  a  groove  for  the 
vena  porta,  before  it  enters  the  pancreatic  ring. 

The  duct  of  this  gland,  known  as  the  duct  of  Wiraung,  lies 


Fig.  107. 
•  Anterior  view  of  the  pancreas,  a.  Left 
branch;  6,  Eight  branch;  c,  Inferior 
branch  ;  d,  Duct  of  Wirsung  ;  e,  Ductus 
pancreaticus  minor ;  /,  Portal  vein  cut 
across ;  g.  Notch  for  the  great  mesenteric 
artery. 


SPLEEN.  31^ 

near  the  superior  surface  of  the  gland,  and  is  formed  by  two  large 
radicals,  right  and  left,  and  in  the  horse  it  enters  the  duodenum 
with  the  hepatic  duct,  in  some  cases  uniting  with  the  latter  to 
form  the  ductus  communis.  There  is  sometimes,  perhaps  always, 
an  accessory  canal  {ductus  pancreaticus  minor)  which  enters  the 
intestine  separately.  The  pancreatic  secretion  is  clear  and 
colourless  ;  it  mixes  with  the  chyme,  and  assists  in  chyiification 
by  emulsifying  the  fatty  material,  and  so  rendering  the  latter  fit 
for  absorption.  The  pancreas  is  supplied  chiefly  by  the  hepatic 
and  anterior  mesenteric  arteries.  Its  nerves  come  from  the  solar 
plexus. 

SPLEEN. 

The  spleen  is  a  soft,  reddish-grey  organ,  situated  on  the  left 
side  of  the  great  curvature  of  the  stomach,  in  the  left  bypochon- 


Internal  aspect  of  the  spleen,  a,  Superior  extremity,  or  base ;  b. 
Inferior  extremity ;  c.  Internal  surface  ;  d  d,  The  hilus ;  e.  Anterior 
border ;  /,  Posterior  border ;  g.  Suspensory  ligament. 

driac  region.  It  is  an  exceedingly  vascular,  ductless  gland,  having 
no  excretory  canal.  In  the  horse  it  varies  in  weight, — from 
about  two  to  four  pounds, — and  is  shaped  somewhat  like  a  scythe 
blade,  the  apex  being  directed  obliquely  downwards  and  forwards. 
It  has  two  surfaces,  two  borders,  and  two  extremities.  The 
superior  or  external  surface  is  somewhat  flat,  and  is  related  with 
the  diaphragm ;  while  the  inferior  or  internal  is  slightly  concave, 
and  contacts  the  large  colon.  The  posterior  border  is  convex, 
thin,  and  sharp;  the  anterior  thick,  concave,  and  grooved  by  the 
splenic  fissure,  or  hilus,  in  which  lie  nerves  and  vessels ;  the 
gastro-splenic  omentum  is' attached  to  this  border.  The  base  or 
superior  extremity,  large,  thick,  and  straight,  is  related  to  the 


320 


SPLANCHNOLOGY. 


left  kidney  and  left  aspect  of  the  pancreas  ;  the  suspensory  liga^ 
ment,  formed  of  a  double  fold  of  peritoneum,  with  a  central  layer 
of  yellow  elastic  tissue,  proceeds  hence  to  the  anterior  border  of 
the  left  kidney  and  abdominal  wall,  becoming  blended  inferiorly 
-vnth  the  great  omentum ;  the  apex  or  inferior  extremity  is  thin, 
and  terminates  in  a  blunt^ point. 

The  spleen  is  soft,  elastic,  tenacious,  distensile,  and  consists  of 
serous  and  fibrous  coats,  and  the  tissue  proper  to  it,  or  parenchyma. 
The  serous  coat  envelops  all  the  organ  but  the  hilus,  and  is  a 
reflection  of  the  peritoneum.      Beneath  this  is  the  proper  capsule, 


Relation  of  anterior  abdominal  digestive  organs— left  antero-lateral  view.  1,  Liver ;  2,  Stomach; 
."3,  Spleen  ;  4,  Colon ;  a,  Gastro-hepatic  omentum  ;  b,  Gastro-splenic  omentum ;  c,  Great  omentum ; 
■  c',  Its  free  portion. 


a  thin,  resisting,  fibrous  coat,  formed  by  connective  tissue  and 
elastic  fibres.  A  number  of  white  glistening  bands,  or  trabeculce, 
pass  into  and  traverse  the  organ,  forming  a  cellular  network, 
in  the  meshes  of  which  is  contained  the  parenchyma  or  splenic 
pulp,  a  red-looking  material,  resembling  grumous  blood,  which 
brightens  in  colour  on  exposure  to  the  atmosphere. 

The  splenic  artery,  which  is  a  branch  of  the  coeliac  axis,  is  very 
large,  and  gives  off  numerous  branches,  which  enter  the  organ, 
enclosed  in  ^heaths  formed  by  the  fibrous  capsule.  Thase  ramify 
and  give  off  branchlets,  which  run  along  the  trabeculas,  and  ter- 
minate in  the  pulp,  in  capillary  plexuses,  supported  by  minute 


THE    PERITONEUM.  321. 

trabeculas  of  connective  tissue.  From  these  spring  the  capillary 
veins,  which  unite  and  finally  form  the  splenic  vein,  which  is  like- 
wise very  large,  and  leaves  the  organ  at  the  hilus.  Some  of  the 
small  arteries  terminate  in  lacunce,  or  intercellular  spaces  of  the 
pulp,  whence  veins  arise.  Embedded  in  the  spleen  pulp  are 
numerous  white  bodies,  the  splenic  vesicles,  or  Malpighian  cor- 
puscles, which  are  attached  to  the  smaller  arteries.  They  consist 
of  a  retiform  lymphoid  tissue,  in  the  meshes  of  which  are  colourless 
lymph  cells  and  capillary  vessels,  the  tissue  itself  being  continuous 
with  the  retiform  tissue  of  the  pulp.  The  nerves  come  from  the 
solar  plexus.  The  spleen  is  regarded  by  some  as  an  internal 
refuge  for  blood  when  cold  is  applied  to  the  superficies  of  the 
body.  Its  use  is  very  obscure ;  some  maintain  that  it  forms 
blood-corpuscles ;  Kolliker,  that  it  is  the  agent  of  their  destruc- 
tion. The  usual  view  now  taken  is  that  the  white  blood-corpus- 
cles are  formed  in  it,  while  the  red  corpuscles  are  broken  up. 
It  appears  not  irrational  to  suppose  that,  becoming  distended 
with  blood  during  digestion,  one  of  its  uses  may  be  to  raise  the 
temperature  of  the  food  in  the  stomach  to  the  degree  required^ 

THE    PERITONEUM. 

The  abdomen  and  part  of  the  pelvis  are  lined  by  the  peri- 
toneum. Like  all  serous  membranes,  it  is  composed  of  a  parietal 
and  visceral  portion,  which  together  form  a  complete  sac,  with 
the  organs  it  covers  situated  on  its  outer  side.  The  internal 
surface  is  smooth,  free,  moist,  and  covered  by  scaly  epithelium  ; 
it 'secretes  a  serous  lubricating  fluid.  The  external  or  attached 
surface  adheres  to  the  inner  parietes  of  the  abdomen  and  pelvis, 
excepting  the  centre  of  the  diaphragm,  and  also  to  the  outer 
surfaces  of  the  viscera,  the  former  constituting  the  parietal,  the 
latter  the  thinner  visceral  portion.  Besides  covering  the  external 
surface  of  the  viscera,  double  folds  pass  from  one  organ  to  another, 
or  from  an  organ  to  the  parietes  of  the  cavity  ;  these  double 
folds  of  peritoneum  are  known  either  as  ligaments,  mesenteries, 
or  omenta.  In  ligaments  the  two  folds  are  strengthened 
by  an  interposed  layer  of  fibro-elastic  tissue.  A  mesentery 
is  a  broad,  double  fold  of  peritoneum,  attached  to  the  abdominal 
parietes  above,  and  containing  a  portion  of  the  intestine  in  its 
free  or  remote  extremity.  Between  its  folds  we  find  blood-vessels,, 
nerves,  and  lymphatics  or  lacteals,  hence  it  permits  vascular  and 
nervous  communication  with  the  organ  attached  to  it. 

The  mesenteries  are   the  mesentery   proper,  a  huge  sheet  of 

Y 


322  SPLiNCHNOLOGY. 

membrane  suspending  the  jejunum  and  ileum  from  the  abdominal 
Toof,  and  commencing  at  the  level  of  the  great  mesenteric  artery ; 
narrow  at  its  origin,  it  becomes  gradually  broader  posteriorly. 
The  meso-colon  attaches  the  great  colon  to  the  abdominal  parietes, 
a  part  uniting  the  upper  and  lower  portions  of  it ;  a  portion  of 
this  structure,  the  meso-ccecum,  covers  the  caecum  in  a  like  manner, 
joining  part  of  it  to  the  colon.  •  The  colic  mesentery,  similar  to 
the  mesentery  proper,  suspends  the  floating  colon, -and  a  continu- 
ation of  it  which  suspends  the  anterior  part  of  the  rectum  is 
termed  the  meso-rectuwi. 

An  omentum  is  a  double  fold  passing  from  one  abdominal 
organ  to  another,  sometimes  establishing  vascular  and  nervous 
communication  between  them.  There  are  three  omenta,  so  called, 
■which  are  continuous  with  each  other.  The  great  or  gastro-colic 
omentum,  stretches  from  the  great  curvature  of  the  stomach  and 
duodenum  to  the  colon  ;  the  gastro-Jiepatic  or  small  omentum, 
extends  from  the  lesser  curvature  of  the  stomach  and  oesophagus 
to  the  liver ;  while  the  gastro-splenic  omentum  passes  from  the 
greater  curvature  of  the  stomach  to  the  hilus  of  the  spleen. 
The  three  omenta  together  include  an  anterior  sac  (bursa  omen- 
talis),  which  communicates  with  the  rest  of  the  serous  cavity  by 
an  aperture  called  the  hiatus  of  Winslow,  situated  between  the 
anterior  end  of  the  right  kidney,  the  pancreas,  and  the  Spigelian 
lobe  of  the  liver. 

In  tracing  the  course  of  the  peritoneum,  it  may  simplify  tho 
matter  to  divide  it  into  two  portions,  a  superior  one,  leaving  the 
abdominal  parietes  above,  and  an  inferior  one,  leaving  the  parietes 
below,  both  passing  along  the  posterior  part  of  the  diaphragm,  at 
the  centre  of  which  they  surround  the  vena  cava,  and  pass  on  to* 
the  liver,  helping  to  form  its  ligaments.  They  then  surround 
that  organ,  one  portion  going  up,  the  other  down  the  anterior 
surface,  round  t^^the  posterior  surface,  which  they  cover,  meeting  at 
thef  posterior  fissure  to  form  the  gastro-hepatic  or  lesser  omentum, 
■which  proceeds  from  the  liver  to  the  lesser  curvature  of  the 
stomach.  The  two  layers  now  cover  the  stomach,  form  the 
coronary  ligament  round  the  oesophagus,  and  again  meet  at  the 
greater  curvature,  forming  on  the  left  the  gastro-splenic  omentum, 
and  passing  to  the  hilus  of  the  spleen,  which  is  covered  by 
them.  On  the  right  the  two  layers  form  the  gastro-colic  or 
^eat  omentum  ;  these  cover  the  colon  and  advance  upv/crd 
towards  the  vertebroe,  formins:  the   meso-colon  and  meso-csecum. 


KESPIEATORY    SYSTEM.  323 

The  two  layers  now  separate ;  the  superior  passes  forwards  along 
the  roof  of  the  abdomen,  and  again  returns  to  the  posterior  part 
of  the  diaphragm.  The  inferior  layer  descends  to  and  envelops 
the  small  intestines,  and  returns  to  the  abdominal  roof,  the 
double  layer  constituting  the  mesentery.  It  now  passes  back- 
wards to  the  iliac  region,  where  it  again  descends  to  suspend  the 
floating  colon  and  the  rectum,  forming  the  colic  mesentery  and 
meso-rectum  by  returning  upwards.  In  the  pelvis  it  forms  the 
recto- vesical  ligament,  between  the  bladder  and  rectum,  finally 
returning  along  the  inferior  parietes  of  the  abdomen  to  the 
diaphragm.  In  the  female,  the  peritoneum,  after  leaving  the 
rectum,  passes  to  the  anterior  surface  of  the  vagina  and  uterus, 
forming  the  broad  ligaments. 

On  the  abdominal  floor,  stretching  forwards  in  the  median  line 
from  the  umbilicus  to  the  quadrate  lobe  of  the  liver,  is  the  broad 
ligament  of  the  latter,  and  in  a  similar  manner,  passing  backwards 
to  the  fundus  of  the  bladder,  we  find  alsO  a  broad  ligament. 
Neither  of  the  latter  structures  are  well  marked  in  the  adult, 
especially  the  last. 

Respiratory  System. 

By  the  action  of  these  organs  certain  chemical  and  physical 
changes  take  place  in  the  blood,  the  chief  of  these  consisting  in 
absorption  of  oxygen  from,  and  giving  off  carbonic  acid  to,  the 
atmospheric  air,  the  former  change  being  necessary  for  the 
elaboration  of  the  fluid,  the  latter  for  the  elimination  of  a  sub- 
stance which,  if  retained,  would  prove  prejudicial.  The  organs 
of  respiration  are  invariably  adapted  to  the  wants  of  the  animal 
and  the  medium  in  which  it  lives.  Thus,  insects  breathe  by  air- 
tubes,  opening  on  the  surface  of  the  body;  in  the  oyster  breath- 
ing is  performed  by  fringes ;  in  fishes  by  gills  ;  in  the  mammalia 
by  means  of  elastic  air-receptacles,  called  lungs,  which  are 
enclosed  in  special  cavities,  and  communicate  with  the  atmos- 
phere by  means  of  an  air- tube. 

In  the  horse,  who  breathes  only  through  his  nose,  the  organs 
of  respiration  are  the  Nostrils,  Nasal  Chambers,  Pharynx,  Larynx, 
Trachea,  and  in  the  thoracic  cavity  the  Bronchi,  Bronchial  tubes, 
and  Lungs. 

THE   nostrils. 

The  nasal  openings,  or  nostrils,  are  two,  right  and  left,  oblong 
-openings,    situated    in    the    anterior    part    of   the    face    at   the 


324 


SPLANCHNOLOGY. 


extremity  of  the  nasal  chambers,  and  disposed   obliquely   from 
above  downwards,  and  without  inwards,  being  slightly  curved  so 
as  to  present  their  concavities  externally.      The  nostrils  consist 
of  an  incomplete  cartilaginous  skeleton  covered  by  muscles,  and 
lined  internally  by  mucous  membrane.      They  are  bounded  by 
movable  wings,  or  alcB,  which  are  covered  within  and  without  by 
a  thin  deliotite  skin,  clothed  with  fine  soft  hairs.      The  external 
wing  is  concave   on  its  free  border,  the  internal  being  convex. 
The  commissures  of  the  alse  are  a  superior  and  an  inferior.      The 
finger  introduced  into  the  superior  commissure  does  not  enter  the 
nasal  cavity,  but  a  conical  cul-de- 
sac,  the  false  nostril,  a  diverticulum 
of  the  nose.      This  cavity  is  formed 
by  the  skin,  and  lies  in   the  space 
between  the    nasal   peak   and    the 
external  process  of  the  premaxillary 
bone.     The  false  nostrils  communi- 
cate freely  with  the  nasal  chambers ; 
their  precise  use  is  unknown,  but 
they    probably    enlarge    the    nasal 
openings  during  respiratory  exertion. 
The    inferior   commissure    is    large 
and    round,   presenting,   at  a  short 
distance  within,  an  opening,  some- 
times double,  which  is  the  inferior 
orifice  of  the  lachrymal  conduit.   In 
the  ass  and  mule  this  opening  is 
situated  on  the  deep  surface  of  the 
external  ala   near   to   the   superior 
commissure. 
Each  of  the  alar  cartilages  resembles  an  incomplete  ring,  the 
incomplete  portion  being  directed  outwards.      They  are  loosely 
attached  to  the  anterior  extremity  of  the  septum  nasi  and  to 
each   other,   and  they   serve  to  keep  the  nostrils  open,   permit 
dilatation,  and  protect  the  nasal  peak.      They  are  divided  into  a 
superior  and  inferior  part.      The  former  is  large  and  flat,  and 
situated  within  the  substance  of  the  internal  ala,  being  covered 
by    the     dilatator    naris     transversalis.       The    inferior    part     is 
prolonged   by  a  blunt  point  to  the  external  ala,  to  which  the 
orbicularis     oris,     dilatator     naris     lateralis,    and     levator     labii 
superioris  alasque  nasi  are  attached.      The  skin  which  covers  the 


Fig.  110. 
Cartilaginous  framework  of  the  nostril 
—seen  fronfabove.    a  a,  Right  alar  carti- 
lage ;  a'  a'.  Left  alar  cartilage  ;  h,  Termi- 
nal portion  of  the  septum  nasi. 


NASAL    CHAMBERS.  325 

nostrils  is  very  thin,  containing  a  quantity  of  pigment,  or 
colouring  material.  It  is  continuous  with  the  mucous  membrane 
of  the  interior,  and  adheres  to  the  muscles  by  dense  fibro-cellular 
tissue. 

The  blood-vessels  are  the  superior  coronary,  nasal,  and  palato- 
labial  arteries  and  veins.  The  nerves  are  derived  from  the  fifth 
and  seventh  pairs. 

In  the  horse  the  power  of  dilating  the  nostril  attains  its 
maximum.  The  use  of  the  nostril  is  to  give  passage  to  the  air 
in  inspiration  and  expiration. 


NASAL    CHAMBERS. 

These  are  cavities  extending  from  the  cribriform  plates  of  the 
ethmoid  bone  to  the  nostrils,  in  a  direction  parallel  to  the  long 
axis  of  the  face,  and  are  separated  from  each  other  by  the  cartila- 
ginous septum  nasi,  which  in  age  undergoes  partial  ossification^ 
and  is  attached  postero-inferiorly  to  the  groove  of  the  vomer. 
Being  continuous  with  the  perpendicular  plate  of  the  ethmoid, 
superiorly  it  rests  in  a  groove  formed  by  the  union  of  the  nasal 
bones,  thus  preventing  any  communication  between  the  chambers. 
Anteriorly,  it  is  expanded  and  attached  to  the  alar  cartilages  of 
the  nostrils.  The  interval  wall  of  the  chambers  is  smooth,  and 
formed  by  the  septum  nasi ;  the  external,  which  is  irregular,  is 
chiefly  formed  by  the  superior  maxilla.  The  roof  is  formed  by 
the  nasal  and  part  of  the  frontal  bones.  The  floor,  broader  and 
shorter  than  the  roof,  is  completed  by  the  palatine  process  of  the 
superior  maxilla  and  the  palatine  bones,  and  is  concave  from 
wall  to  wall.  The  anterior  extremity  contains  the  nasal 
openings.  The  posterior  is  occupied  above  by  the  cells  of  the 
ethmoid  ;  below  is  the  oval  opening  common  to  the  posterior 
nares,  which  communicate  with  the  pharynx.  Each  chamber  is 
divided  by  the  turbinated  bones  into  three  passages,  or  meati ; 
the  superior  lies  between  nasal  and  frontal  bones  above,  and  the 
superior  turbinated  bone  below ;  the  middle  between  the  two 
turbinated  bones,  reaching  to  the  cribriform  plates  of  the  ethmoid 
bone ;  while  the  inferior  is  between  the  inferior  turbinated  bone 
and  the  floor  of  the  chamber. 

The  nasal  chambers  are  lined  by  a  delicate,  pale  rose-coloured 
mucous  membrane,  the  pituitary  or  Schneiderian  membrane, 
which  is  continuous  with  the  skin  at  the  nostrils,  the  mucous 


326  SPLANCHNOLOGY. 

membrane  of  the  pharynx,  and  with  that  lining  the  sinuses  of  the 
head ,  and,  in  some  animals,  with  the  conjunctiva,  by  the  lach- 
rymal duct.  It  is  attached,  and  sometimes  inseparably,  to  the 
perichondrium  of  the  septum  and  the  periosteum  of  the  bones. 
The  pituitary  membrane  is  sensitive,  varying  in  vascularity  and 
thickness,  being  most  vascular  on  the  septum  and  turbinated 
bones,  and  thinnest  in  the  sinuses;  its  free  surface  is  smooth, 
and  covered  by  epithelium.  Near  the  external  opening  the 
epithelium  is  scaly,  the  remainder  ciliated.  It  is  studded  with 
numerous  follicles  or  crypts,  which  secrete  mucus  to  keep  the 
surface  moist,  preserve  its  sensitiveness,  and  defend  it  from 
noxious  vapours.      The  blood-vessels  come  from  the  lateral  nasal 


Longitudinal  section  of  the  head,  showing  the  pharynx  and  nasal  chamber— the  septum  nasi 
being  removed,  a,  Superior  turbinal ;  b,  Inferior  turbinal ;  c,  Superior,  d,  Middle,  and  e,  Inferior 
nacal  meatus  ;  /,  Cavity  of  the  pharynx ;  g.  Opening  of  Eustachian  tube  ;  h,  Isthmus  faucium  ; 
i,  Posterior  naris  ;  k,  Opening  of  the  larynx  ;  I,  Opening  of  the  cesophagus. 

and  spheno-palatine  arteries.  The  nerves  are  the  first  or  olfac- 
tory pair,  or  nerves  of  the  special  sense  of  smell,  and  certain 
branches  of  the  fifth.  The  canal  of  Jacobson  in  the  horse  is  a 
blind  canal,  with  its  orifice  on  the  floor  of  the  nasal  chamber 
about  the  incisive  opening ;  it  runs  backward  for  about  four 
inches,  being  related  with  the  septum  nasi.  Its  use  is  unknown. 
Each  nasal  chamber  communicates  with  four  distinct  sinuses 
— Frontal,  Maxillary,  Ethmoid,  and  Sphenoid,  The  maxillary 
sinus  is  divided  into  two  ;  the  anterior  cavity,  often  called  the 
inferior  maxillary  sinus,  is  generally  isolated  from  the  rest. 
(See  p.  44.)  The  sinuses  are  lined  with  mucous  membrane,  and 
contain  air.      The  laasal  chambers  give  passage   to  the  respired 


LARYNGEAL    CAP.TILAGES.  327 

^ir,  and  are  at  the  same  time  coacerned  in  the  special  sense  of 
;smell. 

The  pharynx  has  been  described  with  the  digestive  organs. 
<See  p.  296.) 

LARYNX. 

This  is  a  complex  musculo-cartilaginous  valve,  situated  at  the 
anterior  extremity  of  the  windpipe.  It  gives  passage  to  air,  and 
at  the  same  time  is  the  organ  of  voice.  The  anterior  extremity 
opens  into  the  pharynx  ;  the  posterior  is  continuous  with  the 
trachea.  It  lies  at  the  posterior  part  of  the  maxillary  space,  is 
directed  obliquely  from  above  downwards  and  backwards,  being 
suspended  below  the  os  hyoides,  and  united  by  one  of  its 
cartilages  to  the  extremity  of  the  heel  process  on  either  side. 
It  is  attached  to  the  pharynx  by  muscles,  and  partly  supported 
by  the  trachea. 

LARYNGEAL   CARTILAGES. 

The  cartilages  which  form  the  larynx  are  seven  in  number, 
three  single  ones,  and  two  pairs.  The  former  are  the  Cricoid, 
Thyroid,  and  Epiglottis ;  the  latter,  the  Arytenoid  and  Cuneiform 
cartilages. 

The  cricoid,  or  ring-like  cartilage,  is  situated  at  the  base  of 
the  larynx,  surrounding  the  air  passage.  It  is  narrow  and  convex 
infero-anteriorly ;  deep  and  broad  postero-superiorly.  It  presents 
two  surfaces  and  two  borders.  The  internal  surface  is  smooth, 
and  covered  by  mucous  membrane ;  the  external  one  postero- 
superiorly  presents  in  the  median  'line  a  longitudinal  ridge,  to 
which  are  attached  a  few  longitudinal  fibres  of  the  oesophagus. 
On  either  side  of  the  ridge  is  a  broad  concavity,  in  which  rests 
the  crico-arytenoideus  posticus  ;  while  on  each  side  of  the  con- 
cavities is  a  small  protuberance  for  articulation  with  the  posterior 
cornu  of  the  thyroid  cartilage.  The  superior  border  bounding 
the  oval  orifice  is  directed  obliquely  upwards  and  backwards,  and 
comprised  between  the  two  branches  of  the  thyroid.  On  either 
side  of  this  border  is  a  smooth,  convex  surface  for  articulating 
with  the  arytenoid  cartilages.  The  inferior  border  is  level,  and 
encircles  the  upper  part  of  the  first  ring  of  the  trachea,  to  which 
it  is  attached. 

The   thyroid,   or  shield-like  cartilage,   i.5   the   largest   in  the 


328  SPLANCHNOLOGY. 

lar^-nx.  It  consists  of  two  lateral  expansions  or  alee,  ■which  meet 
.and  unite  antero-superiorly  at  a  rather  acute  angle,  forming  a 
projection  called  the  body  of  the  thyroid,  equivalent  to  .the 
pomum  Adami  in  man.  Its  inferior  surface  is  smooth,  giving 
attachment  to  a  tendon  of  the  sterno-thyro-hyoideus.  On  the 
superior  surface  is  a  blunt,  irregular  protuberance,  with  which 
the  epiglottis  articulates.  The  alse  are  quadrilateral,  slightly 
convex  externally,  and  clothed  by  the  attachments  of  the 
hyo-thyroid  and  thyro-pharyngeal  muscles.  They  are  slightly 
concave  internally,  and  covered  postero-superiorly  by  mucous 
membrane.  From  the  angle  of  the  wings  anteriorly  and  internally 
spring  the  thyro-arytenoideus  muscles,  the  thyro-arytenoidean 
ligaments  or  vocal  cords,  and  the  thyro-epiglottidean  ligament  ;. 
to  the  inferior  border  the  crico-thyroid  ligament  is  attached,  to- 
the  superior  the  hyo-thyroid  ligaments.  Posteriorly,  eack 
■wing  terminates  in  two  cornua.  The  superior  inclines  upward, 
and  is  attached  by  fibro-cartilage  to  the  extremity  of  the  heel 
process  of  the  os  hyoides ;  the  inferior,  the  larger  and  morfr 
prouiiuent,  articulates  with  the  small  protuberance  on  the 
posterior  surface  of  the  cricoid  cartilage. 

The  arytenoid,  or  ewer-shaped  cartilages,  a  pair,  lie  upon  the 
cricoid,  and  bound  supero-posteriorly  the  entrance  of  the  larynx. 
They  are  irregularly  pyramidal,  each  presenting  two  surfaces,  four 
borders,  and  an  apex.  The  internal  surface  is  smooth,  and  covered 
by  mucous  membrane  ;  the  external  is  divided  by  a  ridge  into 
two  portions;  a  superior  which  is  covered  by  the  arytenoid  muscle, 
and  an  inferior  which  receives  the  attachment  of  the  crico- 
arytcuoideus  lateralis  and  thyro-arytenoideus.  The  inner  border 
unites  with  its  fellow;  the  posterior  one,  forming  the  base,  is  turned 
backwards,  and  receives  the  attachment  of  the  crico-arytenoideus 
posticus  the  outer  angles  articulating  with  convexities  on  the  side 
of  the  superior  border  of  the  cricoid  cartilage.  The  anterior 
border  is  thick,  and  covered  by  mucous  membrane,  while  the 
inferior  border  receives  the  insertion  of  the  vocal  cords.  The 
apex  formed  in  front  by  the  junction  of  the  two  arytenoids  is 
prolonged  by  two  pieces  of  fibro-cartilage,  the  cornicula  laryngis, 
which  pass  outwards  and  backwards,  forming  a  spout  or  lip,  in 
which  rests  the  epiglottis,  when  the  larynx  is  closed. 

The  epiglottis  is  a  soft,  leaf-like  cartilage,  flexible,  and  situated 
in  front  of  the  opening  of  the  larynx,  which  it  completely  closes 
during  the  passage  of  food  through  the  pharynx  into  the  oeso- 


LARYNGEAL  LIGAMENTS.  329 

phagus.      Ics  anterior  surface,  somewhat  convex,   is  attached  to 

the  tongue,  by  the  glosso-epiglottidean  ligaments,  and  to  the  hyoid 

hone  by  the   hyo-epiglottidean    muscle. 

The     posterior    surface    is    rough,     and 

studded  with  numerous  mucous  glands. 

The  base  articulates  with   the   posterior 

part     of    the     body     of     the     thyroid. 

The  apex  is  free,  and  somewhat  curved 

forwards.    From  the  base  of  the  epiglottis, 

two  lateral  processes  extend  backwards  : 

these  are  the  cunieforTii  cartilages,  and 

they  are  situated  in  the  folds  of  mucous 

membrane  which   stretch  from   the   epi-        _  ,  .     .'""  /', 

^  Posteriorview  of  the  epiglottis, 

glottis    to    the    arytenoid  cartilages,   being        a, Base;  6 6, Cuneiform  cartilages; 

attached  to  the  latter  by  elastic  ligaments,      ''  ^"^'"" '  '^  ^'  ^^'''''  ^''^'''■ 
together  forming  the  false  vocal  cords. 


LARYNGEAL   LIGAMENTS. 

The  ligaments  connected  with  the  larynx  are  extrinsic  and 
intrinsic.      The  extrinsic  ones  are  as  follows : — 

Lateral  Hyo-thyroid.  I  Hyo-epiglottidean. 

Middle  Hyo-thyi'oid.  I  Crico-trachealis. 

The  later al-hyo- thyroid  pass  from  the  superior  border  of  the 
thyroid  cartilage  to  the  heel  process  of  the  os  hyoides.  The 
■middle  hyo-thyroid  ligament  is  a  broad  membrane,  filling  up  the 
space  between  the  anterior  border  of  the  thyroid  cartilage  and  the 
lieels  and  body  of  the  os  hyoides.  The  hyo-einglottidean  ligament 
is  a  band  of  yellow  elastic  tissue,  running  between  the  base  of  the 
epiglottis  and  body  of  the  os  hyoides,  covered  by  the  hyo-epiglotti- 
dean muscle.  The  crico-trachealis  ]o\x\^  the  cricoid  cartilage  to 
the  trachea. 

The  intrinsic  ligaments  are  : — 

Thyro-epiglottidean.  i  Crico-arytenoideau. 

Arytenoidean.  |  Crico-thyroideau. 

Thyro-arytenoideau. 

The  thyro-epiglottidean  ligament  binds  the  base  of  the  epi- 
glottis to  the  superior  border  of  the  thyroid  cartilage.  The 
-arytenoidean  ligament  joins  the  two  arytenoid  cartilages  together. 


330 


SPLANCHNOLOGY. 


The  crico-arytenoldean  ligaments  connect  the  outer  angles  of  tli& 
arytenoid  with  the  superior  border  of  the  cricoid  cartilages.     Th& 
crico-thyroidean  ligaments,  three  in  number,  connect  the  cricoid 
and  thyroid  cartilages  ;  they  consist  of  an  anterior  or  broad  one^ 
and  two  lateral  ones  attached  to  the  posterior  extremities  of  the- 
thyroid  wings.      The  thyro-arytenoidean  ligaments  are  likewise 
known  as  the  true  vocal  cords,  and  they  stretch  from  the  inner 
aspect  of  the  angle  of  the 
thyroid     cartilage    to    the 
base  of  the  arytenoid  carti- 
lages.     The   superior  aper- 
ture  of  the  larynx,  which, 
when    open    communicates 
with  the  pharynx,  is  some- 
what   oval,    and     bounded 
anteriorly  by  the  epiglottis, 
posteriorly  by  the  arytenoids 
and  cornicula  laryngis,  later- 
ally by  the  false  vocal  cords. 
Inside  itbecomes  constricted, 
leaving  a  narrow  triangular 
fissure  running   antero-pos- 
teriorly,  and  bounded  later- 
ally   by    folds    of    mucous 
membrane,  in  which  lie  the 
thyro- arytenoid    ligaments 
or   true  vocal  cords.      The 
narrow  opening  of  the  lar- 
ynx between  the  right  and 
left  vocal  cords  is  called  the 
rima    r/loitidiff,   or  i/lottis, 
and  is  wider  posteriorly  from 
the  divergence  of  the  cords. 
Between  the  true  and  false 
vocal  cords,  on  either  side,  is  a  deep  ovoid  fossa,  the  lateral  sItius^ 
or  ventricle  of  the  larynx  ;    at  the  base  of  the  epiglottis  is  a 
third,  small,  blind  depression,  the  middle  ventricle.     The  inferior 
opening  of  the  larynx  which  communicates  with  the  trachea  ia 
nearly  circular. 


Fia.  113. 
Larynx,  hyoid  bone, 
and  commencement  of 
trachea— posterior  view. 
1,  Epiglottis ;  2,  Left  ary- 
tenoid ;  3,  Posterior  ridge 
of  cricoid  cartilage.  Liga- 
ments—'t,  Hyo-epiglotti- 
dean  ;  b,  Thyro-epiglotti- 
dean  ;  c,  Aryteuoidean  ; 
(I  d,  Crico-arytennidean  ; 
e  e,  Lateral  crico-thyroi- 
dean —  the  epiglottis  is 
fastened  down. 


Via.  114. 
Larynx,  hyoid  bone,, 
and  commencement  of 
trachea— anterior  view. 
1,  Thyroid,  2,  Cricoid  car- 
tilages. Ligaments — a, 
Hyo-thyroid ;  a',  Lateral 
portion  of  the  same;. 
b,  Crico-thyroidean  ;  c» 
Crico-trachealis. 


LARYNGEAL  MUSCLES.  '       331 


LARYNGEAL  MUSCLES. 

The  muscles  of  the  laryax  are  extrinsic,  or  those  arising 
from  neighbouring  parts,  and  intrinsic,  or 'those  acting  between 
the  different  cartilages.  The  extrinsic  muscles  are  three  in 
number : — 

Sterno-thyro-hyoideus.  |  Hyo-thyroideus. 

Hyo-epiglottideus. 


STERNO-THYRO-HYOIDEUS. 

(See  page  179.) 

HYO-THYROIDEUS. 
^FiG.  115.  0.) 

This  is  a  triangular  muscle,  its  fibres  running  backwards  and 
downwards. 

Origin. — The  inferior  border  of  the  heel  process  of  the  os 
hyoides. 

Insertion. — To  a  line  on  the  external  side  of  the  wing  of  the 
thyroid  cartilage. 

Action. — To  depress  the  os  hyoides,  or  elevate  the  larynx. 

HYO-EPIGLOTTIDEUS. 

(Fig.  115.  a.) 

Single  and  fusiform,  this  muscle  is  usually  enveloped  in 
adipose  tissue. 

Origin. — The  middle  of  the  body  of  the  os  hyoides. 

Insertion. — The  inferior  part  of  the  anterior  surface  of  the 
epiglottis,  covered  by  the  mucous  membrane. 

Action. — To  draw  the  epiglottis  forward,  and  thus  open  the 
larynx. 

The  intrinsic  muscles  consist  of  four  pairs  and  one  single 
muscle,  as  follows  : — 

Crico-thyroideus.  [  Crico-arytenoideus  lateralis 

Crico-arytenoideus  posticus.  |  Thyro-arytenoideus. 

Arytenoideus. 


SPLANCHNOLOGY. 


CRICO-THYROIDEUS. 

(Fig.  115.  c.) 

This  is  a  small  muscle  whose  fibres  run  upwards  and  backwards. 
Origin. — The  external  surface  of  the  cricoid  cartilage. 

Insertion. — To  the  posterior  border 
of  the  thyroid  cartilage. 

Action. — To  shorten  the  larynx  by 
drawing  the  two  cartilages  together. 


CRICO-ARYTENOIDEUS   POSTICUS. 

(Fig.  116.  6.) 

The  most  powerful  of  the  intrinsic 
muscles,  this  is  situated  on  the  infero- 
posterior  aspect. 

Origin. — The  cavity  on  the  poste- 
rior surface  of  the  cricoid  cartilage, 
whence  its  fibres  converge  upwards 
and  outwards. 

Insertion. — To  the  posterior  tuber- 
cle  of  the  arytenoid  cartilage,  covered 
by  the  oesophagus  and  crico-pharyngeus 
muscle. 

Action. — To  dilate  the  entrance  of  the  larynx,  and  also  the 
glottis  by  separating  the  vocal  cords. 


Fig.  115. 
Muscles  of  the  larynx— left  lateral 
view,     a,  Hyo-epiglottldeus  ;   b,  Hyo- 
thyroideus ;  c,  Crico-thyroideus. 


CRICO-ARYTENOIDEUS    LATERALIS. 
(Fig.  116.  c.) 

This  muscle  is  triangular  in  shape,  and  lies  between  the  wing 
of  the  thyroid  and  the  arytenoid  cartilage. 

Origin. — The  side  of  the  anterior  border  of  the  cricoid  cartil- 
age, passing  upwards. 

Insertion. — To  the  outer  tubercle  at  the  base  of  the  arytenoid 
cartilage  outside  the  posticus. 

Action. — To  contract  the  opening  of  the  larynx,  and  thus 
antagonise  the  posticus. 


LARYNGEAL    MUSCLES. 


333 


THYRO-ARYTENOIDEUS. 
(Fig.  116.  d.) 

Situated  on  the  inner  side  of  the  wing  of  the  thyroid  cartilage, 
it  consists  of  two  bundles,  separated  by  the  ventricle  of  the 
glottis. 

Origin. — From  the  inner  surface  of  the  angle  of  the  thyroid 
cartilage,  outside  of  the  vocal  cord. 

Insertion. — To  the  middle  line  at  the 
junction  of  the  arytenoid  cartilages. 

Action. — To  constrict  the  glottis.  By 
its  relation  with  the  vocal  cord  this  muscle 
powerfully  influences  the  tension  of  the 
same,  and  consequently  the  voice. 


ARYTENOIDEUS. 

(Fig.  116.  a.) 

This  muscle,  the  smallest  of  the  group,  is 
single,  and  situated  upon  the  arj^tenoid 
cartilages,  stretching  from  one  cartilage  to 
the  other,  the  fibres  intercrossing  in  the 
median  line. 

Action. — To  approximate  the  cartilages, 
and  thus  constrict  the  glottis. 

The  mucous  membrane  is  continuous  with 
that  of  the  tongue  and  pharynx,  forming, 
from  the  tongue  to  the  epiglottis,  the  glosso- 
epiglottidean  folds.  It  is  reflected  over  the 
posterior  face  of  the  epiglottis  to  the  anterior 
part  of  the  arytenoids,  covering  the  lateral 
Iboundary  of  the  laryngeal  opening.  In 
these  folds  lie  the  cuneiform  cartilages.  It 
thus  passes  over  the  false  vocal  cords,  lining  the  ventricles,  and 
returning  over  the  true  vocal  cords  ;  it  clothes  the  inner  surface 
of  the  cricoid  cartilage  and  middle  of  the  crico-thyroid  ligament, 
and  so  is  prolonged  into  the  trachea.  It  is  very  thin,  and  exqui- 
sitely sensitive,  especially  about  the  glottis  ;  it  is  covered  with 
ciliated  epithelium,  and  studded  with  mucous  glands,  which 
moisten    it    and    preserve    its    sensitiveness.       The    glands    are 


Fig.  116. 

Muscles  of  the  larynx — 
left  lateral  view— the  thyiDid 
wing  being  removed.  a, 
Arytenoideus ;  6,  Crico-ary- 
tenoideus  posticus  ;  c,  Crico- 
arytenoideus  lateralis  ;  d. 
Thyro-arytenoideus. 


334 


SPLANCHNOLOGY. 


Cavity  of  the  larynx — opened  posteriorly, 
oo,  Lateral  ventricles  of  the  larynx  ;  b,  Middle 
ventricle  ;  c  c,  True  vocal  cords. 


numerous  on  the  posterior  as- 
pect of  the  epiglottis,  in  front 
of  the  arytenoids,  and  in  the 
laryngeal  ventricles. 

The  larynx  is  supplied  with 
blood  from  the  laryngeal  arteries. 
The  nerves  are  from  the  superior 
and  inferior  laryugeal  branches 
of  the  vagus  ;  twigs  also  come 
from  the  sympathetic. 

The  larynx  gives  passage  to 
the  air  of  respiration,  prevents 
the  intrusion  of  food  into  the 
air-tubes  by  closure  of  its  lid, 
the  epiglottis ;  and  it  contains 
the  organ  of  voice,  the  latter 
being  produced  by  vibration  of 
the  true  vocal  cords. 


TRACHEA. 

The  trachea,  or  windpipe,  is  a  nearly  cylindrical,  and  flexible 
tube,  consisting  of  a  series  of  incomplete  cartilaginous  rings.  It 
succeeds  the  larynx,  runs  down  the  neck,  enters  the  thorax,  and 
terminates  at  the  base  of  the  heart,  where  it  divides  into  the 
right  and  left  bronchi.  Like  the  neck,  it  varies  in  length,  and 
consists  of  forty  or  fifty  rings,  the  ends  of  which  overlap  pos- 
teriorly, forming  a  perfect  expansile  tube.  It  presents  a  number 
of  transverse  furrows,  which  correspond  to  the  interspaces  between 
the  rings.  The  latter  vary  in  depth,  averaging  half-an-inch,  and 
they  are  completed  and  united  by  strong  elastic  ligaments.  The 
first  is  attached  to  the  cricoid  cartilage  by  a  band  called  the 
crico-trachealis  ligament.  The  ligaments  contain  involuntary 
muscular  fasciculi,  and  they  are  attached  by  their  extremities  to 
th©  inner  and  posterior  surface  of  the  rings,  and  to  their  ends,  so 
completing  each  ring. 

The  entire  trachea  is  lined  by  mucous  membrane,  which  is 
continuous  with,  but  not  so  sensitive  as  that  of  the  larynx  ; 
it  is  clothed  with  ciliated  epithelium,  and  studded  with  glands. 
The  trachea  is  related  with  the  oesophagus  and  carotid  arteries, 
the  latter  running  along  its  sides.      The   arteries  supplying  the 


BRONCHI — BRONCHIAL  TUBES.  335 

anterior  and  middle  parts,  consist  of  twigs  from  the  carotid  ; 
posteriorly  the  supply  comes  from  the  broncho-cesophageal ;  th& 
nerves  are  derived  from  the  recurrent  and  sympathetic. 


THYROID  AND  THYMUS  GLANDS. 

About  the  two  first  tracheal  rings  is  the  brownish-red,  thyroid 
body,  consisting  of  two  lobes,  right  and  left,  joined  by  a  narrow 
band,  the  isthmus.  Each  lobe  is  ovoid,  and  consists  of  minute 
vesicles  surrounded  by  a  plexus  of  capillaries,  and  connected  by 
areolar  tissue.  The  gland  is  ductless,  but  copiously  supplied 
with  blood  by  branches  of  the  carotid,  and  secretes  an  albumin- 
ous fluid,  which  is  perhaps  absorbed  by  the  lymphatics,  and 
conveyed  into  the  blood.  It  is  very  large  in  foetal  life,  but  its 
use  is  unknown. 

The  thymus  is  another  ductless  gland,  situated  on  the  inferior 
aspect  of  the  trachea,  and  above  the  sternum.  It  consists  of 
two  halves  united  by  areolar  tissue,  and  is  composed  of  lobules. 
disposed  round  a  central  canal,  having  no  external  openino". 
Within  are  vesicles  similar  to  those  of  the  thyroid  body ;  in  the 
foetus  it  is  attached  to  the  thyroid,  and  is  large  iat  birth, 
gradually  disappearing. 


BRONCHI — BRONCHIAL  TUBES. 

The  terminal  branches  of  the  trachea  are  the  right  and  left 
bronchi,  which  enter  the  lungs  and  subdivide  dichotomously  inta 
branches  termed  bronchial  tubes,  the  latter  becoming  gradually 
smaller,  and  finally  terminating  in  the  air-cells.  The  entire 
ramification  when  isolated  has  the  appearance  of  a  tree,  the 
trachea  being  the  main  trunk,  the  bronchi  and  bronchial  tubes 
the  branches,  and  the  air-cells  the  leaves.  These  structures  are 
accompanied  throughout  by  the  arteries,  veins,  and  nerves,  which 
Lave  the  same  arborescent  distribution.  The  right  bronchus  is 
the  larger,  the  left  the  longer,  since  it  passes  under  the  aorta  before 
reaching  the  lung. 

The  bronchi  and  bronchial  tubes  are  made  up  of  cartilaginous 
rings,  differing  only  from  those  of  the  trachea  in  being  made  up 
of  several  pieces,  which  overlap  and  are  united  by  cellular  tissue 
on  their  inner  surface.  As  the  tubes  diminish  in  size,  the  num- 
ber of  these  pieces  is  diminished,  and  ultimately  they  disappear. 


S36 


SPLANCHNOLOGY. 


The  small  bronchial  tubes,  after  ramifying  in  the  lungs,  terminate 
in  cellular  recesses  or  air-cells,  which  consist  only  of  the  lining 
membrane  of  the  tubes.  The  muscular  bauds  of  the  trachea  are 
■continued  along  the  inner  face  of  the  rings  of  the  bronchi  and 
larger  bronchial  tubes,  also  gradually  disappearing.  These  tubes 
are  lined  by  mucous  membrane,  which  is  continuous  with,  but 
more  sensitive  than  that  of  the  trachea.  Blood  is  supplied  by 
the  bronchial  arteries. 

At  the  root  of  each  lung  there  are  a  number  of  absorbent 
T3ronchial  glands.  The  principal  ones  are  closely  adherent  to  the 
bifurcations  of  the  bronchi 


Fig.  118. 
Genera!  view  of  the  respiratory  organs,  a,  Septum  nasi ;  b,  Posterior  naris ;  c,  Larynx;  d.  Trachea ; 
«,  Thyroid  gland ;  //,  Anterior  mediastinum ;   g  g,  Posterior  mediastinum ;   h.  Left  lung ;  h',  Its 
apex ;  h"  Its  base  ;  h'",  Its  superior,  and  h"".  Its  inferior  borders. 


THORAX. 

The  thorax,  or  thoracic  cavity,  is  formed  by  the  ribs,  sternum, 
and.  bodies  of  the  dorsal  vertebrae,  the  intercostal  muscles, 
thoracic  fascia,  and  diaphragm  ;  it  contains  the  lungs,  the  heart 
and  its  adjuncts,  the  trachea,  oesophagus,  and  a  quantity  of 
nerves  ;  it  resembles  a  hollow  horizontal  cone,  flattened  from  side 
to  side.  Its  base,  formed  by  the  diaphragm,  slopes  obliquely 
downwards  and  forwards. 


337 


The  thorax  is  lined  by  two  serous  membranes,  the  right  and 
left  pleuras,  which  consist  of  parietal  and  visceral  portions,  and  forpi 
distinct  sacs.  Each  pleura  lines  one  side  of  the  thorax  and  half 
of  the  diaphragm ;  the  pleura  costalis  is  the  portion  lining  the 
ribs  and  intercostal  spaces,  the  pleura  diaphragrsiatica  is  that 
covering  the  diaphragm ;  in  the  median  longitudinal  plane  it 
forms  with  the  opposite  pleura  the  mediastinum,  whence  each  is 
reflected  over  one  of  the  limgs,  forming  the  pleura  pulmonalis. 
The  mediastinum  is  therefore  a  longitudinal  passage  through 
the  thorax,  bounded  on  each  side  by  a  pleural  fold  ;  it  is  divided 
into  three  portions — the  anterior  mediastinum  lies  in  front  of  the 
heart,  the  middle  contains  it,  while  the  posterior  Ues  behind  it. 
The  mediastina  are  occupied  by  the  trachea,  oesophagus,  heart, 
vessels,  and  nerves,  and  the  anterior  one  in  the  foetus  by  the 
thymus  gland. 

In  tracing  the  course  of  a  pleura,  if  we  commence  on  the 
lateral  aspect  of  the  bodies  of  the  dorsal  vertebrae,  we  find  that  it 
extends  downwards  over  the  inner  surfaces  of  al]  the  ribs  and 
intercostal  spaces,  forming  the  pleura  costalis ;  posteriorly  it  passes 
to  the  anterior  convex  surface  of  the  diaphragm,  constituting  the 
pleura  diaphragmaticaj  At  the  centre  of  the  sternum  it  is 
reflected  upwards  between  the  lungs,  enclosing  the  pericardial 
sac.  Gaining  the  root  of  the  lung,  the  parietal  portion  passes  on 
to  it,  forming  the  visceral  portion  or  pleura  palmonalis,  clothes 
the  free  surface  of  the  lung,  and  again  on  the  lung  root  it  is 
reflected  up  to  the  vertebra,  returning  to  its  place  of  origin.  The 
pleura  is  thick  and  loosely  attached  over  the  ribs,  attenuated  over 
the  diaphragm  and  pericardium,  and  extremely  so  on  the  lungs  ; 
its  surface  is  smooth  and  glistening,  emitting  a  vapoury  fluid, 
which  lubricates  the  contacting  surfaces  and  facilitates  motion. 
The  posterior  mediastinum  is  cribrated  inferiorly,  several  open- 
ings leading  from  one  pleural  sac  to  the  other.  This  arrange- 
ment is  peculiar  to  solipedes,  and  explains  the  fact  that  in  these 
animals  there  cannot  be  pleural  effusix)n  confined  to  one  side  of 
the  chest. 

LUNGS. 

The   lungs,    the    essential    organs   of  respiration,    are   spongy 
organs  of  a  conical  shape,  situated  in  the  thoracic  cavity,  right 

z 


333  SPLANCHNOLOGYo 

and  left,  the  former  being  a  little  the  larger ;  they  are  separated 
by  the  mediastinum,  heart,  pericardium,  and  large  blood-vessels. 
During  life,  they  occupy  the  major  part  of  the  cavity,  resting  on 
the  inner  surface  of  the  walls,  and  adapting  themselves  to  its 
varying  capacity.  They  are  light,  porous,  and  highly  elastic, 
possessing  considerable  strength.  Healthy  lungs  float  in 
water,  their  buoyancy  being  due  to  the  air  they  always  contain ; 
when  air  is  admitted  into  the  thorax,  they  collapse  considerably. 
In  the  adult,  they  are  of  a  rosy  flesh  colour,  marked  by  an 
irregular  marbling  or  mottling. 

The  lung  is  attached  midway  by  the  root,  'which  consists  of  the 
bronchus,  vessels,  and  nerves,  enveloped  by  the  pleura.  Each 
lung  presents  two  surfaces,  external  and  internal,  a  base,  an  apex, 
and  three  borders.  The  external  costal  surface  is  convex,  corre- 
sponding to  the  thoracic  wall.  The  internal,  or  mediastinal 
surface,  forms  a  vertical  plane  in  contact  with  the  mediastinum, 
and  presents  an  anterior  division,  which  rests  against  the  anterior 
mediastinum,  in  front  of  an  excavation  in  which  the  heart  is 
lodged  ;  above  and  behind  this  is  the  root  of  the  lung.  Two 
fissures  present  themselves  on  the  superior  aspect,  an  anterior 
and  posterior.  The  former  crosses  towards  the  superior  border, 
and  receives  the  posterior  aorta ;  the  latter,  lower  down,  shallower, 
and  more  distinct  in  the  left  lung,  is  destined  for  the  passage  of 
the  CBSophagus.  On  the  inner  aspect  of  the  right  lung  there  is  a 
«mall  lobule,  wanting  on  the  left  lung,  formed  by  a  deep  fissure, 
through  which  the  posterior  vena  cava  passes ;  it  is  lined  by  a 
fold  of  pleura.  The  concave  base  is  sloped  downwards  and 
forwards,  fitting  the  convex  surface  of  the  diaphragm,  where  the 
:fissure  above  noted  originates.  The  summit  or  apex  lies  behind 
the  first  rib,  and  presents  a  partially  detached  appendage,  the 
anterior  lobe.  The  superior  border  is  round,  thick,  and  convex, 
and  is  lodged  in  the  channel  between  the  ribs  and  bodies  of 
the  vertebrae.  The  inferior  border  is  thinner  and  shorter,  deeply 
cleft  near  the  heart,  and  more  so  on  the  left  than  on  the  right 
side.  The  posterior  border  is  elliptical,  surrounding  the  base, 
which  it  separates  from  the  costal  and  mediastinal  surfaces. 

Structurally,  the  lungs  consist  of  an  external  serous  coat,  a 
subserous  layer,  and  the  long  tissue  proper,  or  parenchyma.  The 
serous  coat  is  the  pleura  pulmonalis.  The  subserous  layer  is  com- 
posed of  cellular  tissue,  intermixed  with  yellow  elastic  fibres ;  it 
clothes  the  entire  lung  surface,  and  is  continuous  with  the  inter- 


LUNGS.  339 

lobular  cellular  tissue.  The  parenchyma  is  divided  into  many 
polyhedral  lobules  of  various  sizes,  united  by  connective  tissue ; 
these  are  again  made  up  of  smaller  ones,  which  are  composed  of 
a  small  bronchial  tube  and  its  terminal  air-cells,  in  the  walls  of 
which  lie  the  capillary  vessels  uniting  the  pulmonary  arteries  with 
the  pulmonary  veins.  The  air-cells  are  vesicular  cavities,  arranged 
as  it  were  in  bunches  at  the  end  of  the  tube ;  they  consist  of  a 
thin  membrane  of  connective  and  elastic  tissue,  with  a  layer  of 
pavemental  epithelium.  Each  lobule  is  provided  with  its  own 
bronchial  tube  and  air-cells,  functional  and  nutritive  vessels, 
lymphatics,  nerves,  and  interstitial  cellular  tissue,  and  is 
enveloped  by  the  interlobular  tissue.  The  interlobular  cellular 
tissue  is  very  fine,  and  continuous  with  the  subserous  layer. 
The  lobular  division  is  constant  in  all  mammiferous  animals  ; 
in  the  horse  it  is  less  distinct 
than  in  ruminants,  where 
there  is  a  much  larger 
amount  of  interlobular  cell- 
ular tissue. 

The  pneumonic  functional 
vessels  are  the  pulmonary 
artery  and  veins.  The  artery 
conveys  venous  blood  from 
the  heart  to  the  lungs.  At 
the  lung-root  it  divides  into 
right    and    left    branches,  fio.  119. 

which     are      distributed      to  Arrangement  of  capillariea  round  the  air-ceUs  ot 

their    respective    lungs,   in 

company  with  the  ramifying  bronchial  tubes,  terminating  in  a 
capillary  network  around  the  terminal  air-cells,  whence  arise  the 
radicles  of  the  pulmonary  veins,  which  return  the  purified  blood 
from  the  lungs  to  the  heart. 

The  nutrient  vessels  are  the  bronchial  arteries  and  .veins. 
These  arteries  proceed  from  the  posterior  aorta;  their  branches 
are  smaller  than  the  pulmonary,  and  also  accompany  the  air- 
tubes.  The  pulmonary  lymphatics  are  numerous,  and  divided 
into  superficial  and  deep.  The  former  are  situated  in  the 
subserous  layer,  forming  a  network,  the  latter  in  the  interlobular 
tissue.  Both  communicate  at  the  lung-roots,  and  pass  through 
the  bronchial  glands.  The  nerves  are  from  the  pulmonary 
plexus,  formed  by  the  vagus  and  s^onpathetic. 


340  SPLANCHNOLOGY. 


Ukinaky  System. 


The  organs  of  tbis  system  secrete  tbe  urine  from  the  bloody 
and  excrete  or  expel  it  from  the  body.  These  organs  are 
chiefly  the  Kidneys,  Ureters,  Bladder,  and  Urethra.  The  urine, 
which  is  a  watery  fluid,  is  secreted  by  the  kidneys,  and  carried 
off  by  their  ducts,  the  ureters,  to  a  special  reservoir,  the  bladder, 
where  it  accumulates,  and  from  which  it  is  finalh'  expelled 
at  intervals  through  the  urethra. 


The  kidneys  are   two   compound   tubular  glands,   situated  on 
the    right   and   left   of   tlie   vertebral  column,  in   the  sublumbar 


Hori;!ontal  section  of  the  right  kidney.  «,  Fibrous  capsule 
detached  ;  b  h  b,  Cortical  layer  ;  <?  c,  MeduUary  layer  :  d  d  d, 
Cut  ends  of  large  blood-vosscls  :  e.  Pelvis  of  the  kidney  • 
/,  Ureter. 

region  of  the  abdomen,  in  contact  with  the  crura  of  the^ 
diaphragm  and  psoe  muscles.  They  are  supported  by  perito- 
neum and  cellular  tissue,  in  which  is  deposited  a  quantity  of  fat ; 
less  perhaps  in  the  horse  than  in  other  herbivorous  animals. 
The  kidneys  are  also  supported  by  their  vessels  as  well  as  by  the 
pressure  of  the  digestive  organs  ;  the  right  one  is  in  advance  of 
the  left,  lying  just  behind  and  beneath  the  last  pair  of  ribs, 
whereas  the  left  one  lies  about  two  inches  farther  back.  They 
somewhat  resemble  in  shape  the  heart  on  playing  cards,  the  left 


KIDNEYS. 


341 


one  being  longer  .and  narrower  than  the  right.      From  perverted 

development,  the  kidney  of  the  horse  is  sometimes  lobulated. 
The  kidney  presents  two  surfaces  and  a  circumference.      The 

surfaces    are    smooth,    the    superior    one    being    flattened,    and 

attached  to  the  muscles  by  cellular  tissue  ;   the  inferior  one  is 

convex,  covered  by  and  attached  to  the  peritoneum.      The  cir- 
cumference is  divided  into  three  borders; 

anterior,  posterior,  and  internal.     The 

t  wo  former  are  convex ;    to   the  first 

is    attached    the    suprarenal    capsule. 

The  internal  border  is  slightly  concave, 

being  deeply  notched    in   the  centre, 

forming  the "  hilus,   which  leads  to  a 

cavity  called  the  sinus.      The  vessels, 

nerves,  and  duct  of  the  kidney  join  it 

in  or  about  the  hilus. 

The  kidney  is  made  up  chiefly  of 

the   tubes  of  the  gland,    termed    the 

uriniferous  tubes,  with  blood-vessels 

and  nerves,  and  connective  tissue  ;   it 

is  invested  by  a  fibrous  capsule,  and 

contains  a  <?avity  known  as  the  pelvis 
of  the  kidney.  The  capsule  invests 
the  entire  organ,  entering  the  hilus 
and  covering  the  sinus,  vessels,  and 
duct.  It  consists  of  thin,  smooth, 
fibro-areolar  tissue,  intimately  con- 
nected with  the  surface  of  the  gland 
by  minute  fibrous  processes  and  blood- 
vessels. On  making  a  horizontal 
section  of  a  kidney,  it  is  found  to 
consist    of   an    external    or    cortical, 


H  H.  Larger  tubes  of  Bellini ;  t,  Smaller 
branch  of  the  same. 


Fig.  121. 
Structure  of  the  kidney.  AAA, Large 
branches  of  renal  artery ;   a  a.  Affer- 
ent vessels  ;  B  B,  Malpighian  bodies  ; 
.  7     77  i^        c  c  c,  Capillary  plexuses  formed  by  effer- 

and    an     internal      or     niedudary    sub-     ent  vessels  ;  d.  Xwlgs  from  renal  artery ; 

stance.  The  cortical  layer  is  situated 
beneath  the  capsule,  sending  pro- 
longations inwards  into  the  medullary  portion.  It  is  dark 
reddish-brown  and  friable,  consisting  of  minute  blood-vessels, 
convolutions  of  the  uriniferous  tubes,  lymphatics,  and  nerves, 
united  by  areolar  tissue.  On  examining  the  section  with  or 
without  a  lens,  numerous  minute  red  points  are  seen  in  the 
coitical    portion,    the     Mcdpighian    bodies.      Each    consists    of 


342 


SPLANCHNOLOGY. 


capilliary  blood-vessels,  arranged  in  a  tuft  or  glomurulus,  sur- 
rounded by  epithelium,  and  enclosed  in  a  membranous  capsule, 
the  capsule  of  Bowman,  which  is  the  dilated  origin  of  a 
iiriniferous  tube.  The  small  branch  of  the  renal  artery,  entering 
the  capsule,  is  the  afferent  vessel  (vas  afferens),  whence  proceed 
the  capillaries  which  form  the  tuft.  The  efferent  vessel  (vas 
efferens),  which  leaves  the  tuft  near  the  afferent  one,  forms  a 
capillary  plexus  round  the  adjacent  tubes,  terminating  in  th^ 
veins.  A  dark  line  separates  the  cortical  from  the  medullary 
layer,  and  has  been  termed  the  limiting  layer,  or  periphery  of  the 
medulla.  In  or  near  this  layer  the  larger  blood-vessels  ramify. 
The  medullary  substance  is  denser  in  structure,  fibrous  in 
appearance,  and  consists  of  pale,  conical 
masses — the  pyramids  of  Malpighi  ;  these 
have  their  bases  directed  outwards,  their 
apices  converging  to  the  pelvis,  and  are 
composed  of  minute  diverging  urinilerous 
tubes,  separated  from  each  other  by  capil- 
lary vessels  and  intermediate  tissue,  similar 
to  that  of  the  cortical  substance.  The 
termination  of  the  pyramids  in  the  pelvis 
varies  in  different  animals.  In  the  horse 
they  terminate  in  a  continuous  ridge,  which 
projects  into  the  pelvis  ;  and  on  the  surface 
of  this  ridge  are  numerous  minute  orifices, 
the  outlets.  In  the  centre  of  the  kidney, 
and  nearly  surrounded  by  the  medullary 
substance,  is  an  irregular  cavity  formed  by 
the  dilatation  of  the  ureter,  the  infundi- 
buluDb,  having  lateral  prolongations  called 
the  arms,  the  whole  constituting  the  pelvis. 

The  urine  secreted  by  the  tubuli  uriniferi  and  Malpighian 
bodies  is  thus  poured  into  the  pelvis.  The  tubes  pass  up  the 
pyramids  in  straight  but  slightly  diverging  lines,  subdividing  at 
very  acute  angles  until  they  reach  the  cortical  substance,  where 
they  dilate  and  become '  tortuous  ;  this  part  has  been  termed  an 
intermediary  tube,  and  from  it  a  constricted  tube  passes  inwards, 
dipping  more  or  less  into  the  medullary  layer,  and  then  returning 
to  the  cortex,  so  forming  a  loop.  To  the  looped  tube  succeeds  a 
second  dilated  portion,  greatly  convoluted,  and  known  as  a  con- 
voluted tube,  which  finds  its  origin  in  a  dilatation — one  of  thft. 


Fio.  122. 
Distribution  of  the  renal 
vessels,  a,  Branch  of  renal 
artery  ;  af.  Afferent  vessels  ; 
m,  Malpighian  tuft ;  ef,  Effer- 
ent vessels ;  p,  Capillary  plex- 
us around  the  uriniferous 
tubes  ;  st,  Straight  tube ;  ct, 
Convoluted  tube. 


XJEETERS.  343 

capsules  of  Bowman.  The  straight  tubes  in  the  medullary  sub- 
stance are  the  tubes  of  Bellini;  the  convoluted  ones  in  the 
cortical  substance,  the  tubes  of  Ferrein ;  while  the  looped  ones 
are  the  tubes  of  Henle.  At  the  base  of  the  pyramids  the  straight 
tubes  form  small  bundles  or  fasciculi,  which  are  prolonged  into 
the  cortical  substance  as  the  pyramids  of  Ferrein.  The  tubuli 
uriniferi  coDsist  of  a  membranous  wall  of  varying  thickness,  lined 
by  epithelium,  which  in  the  straight  tubes  is  columnar  in  form. 

Blood  is  supplied  by  the  renal  artery,  nerves  by  the  solar 
plexus ;  the  latter  ramify  round  the  arteries.  The  superficial 
lymphatics  are  situated  on  the  external  surface,  and  pass  into  the 
lumbar  glands  ;  the  deep-seated  ones  accompany  the  blood-vessels. 

The  function  of  the  kidneys  is  to  secrete  the  urine,  a  fluid 
consisting  of  water,  holding  in  solution  a  varying  quantity  of 
earthy  salts,  and  a  peculiar  nitrogenous  substance,  Urea,  which  if 
not  eliminated,  acts  as  a  blood-poison.  Strange  to  say,  this  efifete 
material  is  secreted  from  arterial,  or  comparatively  pure  blood. 


SUPEARENAL   CAPSULES. 

These  are  two  small,  flat,  reddish-brown  glandular  bodies,  about 
two  inches  long,  attached  to  the  anterior  borders  of  the  kidneys. 
They  are  ductless,  larger  in  the  foetus  than  in  the  adult,  and 
consist  of  a  fibrous  membrane  covering  a  parenchjnna,  which 
consists  of  an  external  cortical  and  an  internal  medullary  sub- 
stance. The  external  substance  is  brown  in  colour ;  the  medullary 
is  yellowish,  soft,  pulpy,  nucleated  and  granular.  The  function 
of  these  glands  is  unknown.  They  are  larger  in  the  foetus  than 
in  the  adult,  and  are  said  to  be  replaced  if  removed. 


ITRETEES. 

The  ureters,  the  excretory  ducts  of  the  kidneys,  are  two 
membranous  canals,  which  convey  the  urine  from  the  pelvis  of 
the  kidney  to  the  bladder.  They  consist  of  three  coats  ;  an 
external  fibro-cellular,  a  middle  muscular,  and  an  internal  mucous, 
lined  with  epithelium  similar  to  that  of  the  bladder.  On  leaving 
the  hilus,  they  are  directed  towards  the  pelvic  cavity,  alongside 
the  aorta  on  one,  and  the  posterior  vena  cava  on  the  other  side, 
and  between  the  peritoneum  and  the  abdominal  roof  On  arriving 
at,  the  termination  of  the  aorta  they  cross  the  iliac  arteries,  covered 


344  SPLANCHNOLOGY. 

by  peritoneum,  which  holds  them  against  the  lateral  walls  of  the 
abdomen  and  pelvis,  terminating  at  the  postero-superior  part  of 
the  bladder,  which  they  enter  on  either  side  by  piercing  its  coats 
in  a  very  oblique  manner,  and  so  leading  to  the  formation  of  a 
valve  which  prevents  regurgitation  of  the  urine. 

The  ureters  are  supplied  with  blood  by  twigs  from  the  renal, 
spermatic,  and  vesical  arteries.  The  nerves  come  from  the 
spermatic  and  hypogastric  plexuses. 

BLADDER. 

The  bladder,  a  musculo-membranous  organ,  serves  as  the 
reservoir  for  the  urine,  and  is  situated  within  the  pelvic  cavity,  and 
when  full  projecting  into  the  abdomen.  It  consists  of  a  fundus, 
or  body,  and  a  neck.  The  fundus  when  full  is  ovoid,  and  turned 
forwards,  having  a  cicatrix,  which  marks  the  site  of  the  urachus. 
The  neck  is  turned  backwards,  and  is  continuous  with  the  urethra. 
The  bladder  is  related  above  with  the  vesiculse  seminales  and 
rectum  in  the  male,  in  the  female  with  the  vagina  and  uterus^ 
which  are  interposed  between  it  and  the  rectum  ;  below  with  the 
floor,  and  laterally  with  the  walls  of  the  pelvis. 

The  bladder  consists  of  three  coats  ;  mucous,  muscular,  and 
serous  ;  The  latter  is  only  a  partial  covering,  being  a  continuation 
of  the  peritoneum,  clothing  the  anterior  part  of  the  organ  ;  it 
becomes  reflected  from  it  in  several  places,  constituting  the  false 
ligaments  of  the  bladder.  The  muscular  coat  consists  of  twa 
layers  of  smooth  muscular  fibres ;  an  external  longitudinal  one,  the 
detrusor  urinoe,  and  an  inner  circular  layer,  thinly  scattered  over 
the  body,  but  denser  at  the  neck,  forming  the  sphincter  vesicae. 
The  sphincter  vesicse  is  less  developed  in  quadrupeds  than  in 
man.  There  are  also  two  bands  of  oblique  fibres  passing  from 
the  posterior  aspect  of  the  ureters  to  the  back  of  the  prostate 
gland. 

The  internal  mucous  coat  is  pale,  smooth,  roseate,  and  loosely 
attached  to  the  muscular  layer  by  cellular  tissue,  which  some 
consider  a  fourth  coat.  It  is  thrown  into  rugcB  when  the  bladder 
is  empty,  and  provided  with  mucous  follicles,  most  abundant  at 
the  neck ;  it  is  covered  by  stratified  epithelium.  Upon  the 
internal  surface,  between  the  openings  of  the  ureters  and  com- 
mencement of  the  urethra,  is  a  smooth  triangular  space,  the 
trigonus  vesicae,  which  is  pale,  sensitive,  intimately  attached  to 


GENERATIVE    SYSTEM.  345 

the  adjacent  tissue,  and  never  thrown  into  rugas.  Projecting 
from  the  posterior  end  of  the  trigonus  into  the  opening  of  the 
urethra,  is  a  slight  elevation  of  the.  mucous  coat,  the  uvula 
vesicce. 

The  bladder  is  maintained  in  position  by  false  and  true  liga- 
ments. The  false  ligaments  are  folds  of  peritoneum,  of  which  the 
anterior  or  broad  one  passes  from  the  fundus  along  the  abdominal 
floor  to  the  umbilicus ;  two  lateral  folds  extend  from  the  sides  of 
the  bladder  to  the  pelvic  walls,  enclosing  in  their  folds  the  remains 
of  the  obliterated  umbilical  arteries ;  finally  a  superior  fold  con- 
nects it  vsdth  the  rectum.  The  remains  of  a  foetal  organ,  the 
urachus,  appearing  as  a  fibrous  cord,  are  generally  described  as 
lying  between  the  folds  of  the  broad  ligament. 

The  true  ligaments  are  formed  by  processes  of  the  pelvic 
fascia.  These  are  the  inferior  true  ligaments,  attached  to  the 
inferior  aspect  of  the  bladder  and  prostate  gland ;  the  lateral 
true  ligaments  which  are  attached  to  the  sides  of  the  organ, 
while  the  recto-vesical  ligament  joins  the  bladder  and  rectum 
posteriorly. 

In  the  female,  the  uterus,  lying  between  the  rectum  and  the 
bladder,  we  have  recto-uterine  and  vesico-uterine  ligaments. 

The  principal  artery  is  the  vesico-prostatic  branch  of  the 
internal  iliac.  Lymphatics  are  numerous  in  the  walls  of  the 
trigonus.  The  nerves  are  from  the  hypogastric  and  sacral 
plexuses. 

The  use  of  the  bladder  is  to  store  the  urine  and  at  intervals, 
by  contraction  of  its  walls  force  it  into  the  urethra  or  excretory 
tube. 

The  Urethra  is  a  tube  common,  in  the  male,  to  the  urinary 
and  genital  systems,  and  will  be  described  with  the  latter. 

Generative  System. 

Animals  possess  the  faculty  of  reproducing  or  propagating  their 
species,  and  this  function  may  be  non-sexual  or  sexual,  the  former 
being  confined  to  certain  lowly-organised  classes  of  animals. 

In  all  the  higher  animals  the  generation  of  a  new  being  is 
dependent  upon  two  individuals,  a  male  and  a  female,  the  female 
furnishing  a  germ  or  ovum,  the  male  a  fecundating  fluid  or  spemiy 
which  animates  the  germ  and  renders  it  fit  for  development. 


346 


SPLANCHNOLOGY. 


Both  the  ovum  of  the  female  and  the  sperm  of  the  male  are- 
the  secretions  of  glands,  which  are  termed  the  genital  glands, 
male  and  female ;  and  in  either  sex  the  generative  system  may- 
be said  to  consist  of  these  glands,  with  certain  accessory  organs. 
The  act  of  coition  brings  the  two  secretions  into  contact. 

We  have  thus  two  systems  of  Genital  organs  to  consider — the- 
•male  and  the  female. 


Fio.  123. 
General  view  of  male  generative  organs— the  abdomen  and  pelvis  being  opened  from  the  left 
Bide,  a,  Scrotum  ;  a',  Skin  ;  a",  Dartos  ;  a'",  Tunica  vaginalis  ;  6,  Cremaster  ;  c,  Left  vas  deferens  ; 
c*.  Its  bulbous  portion  ;  d,  Left  vesicula  seminalis  ;  e,  Prostate  gland  ;  /,  Cowper's  gland  ;  g. 
Sheath  ;  h,  Corpus  cavernosum  ;  i.  Retractor  muscle  of  the  penis  ;  k,  Urethra  surrounded  by 
accelerator  muscle  ;  I,  Erector  penis  muscle  ;  m,  Glans  penis  ;  n,  Meatus  urinarius  ;  c.  Internal 
abdominal  ring  ;  p.  Peritoneal  fold,  enclosing  spermatic  vessels  and  nerves  ;  q.  Right  vas  deferens: 
r,  Bladder  ;  s,  Rectum. 


MALE    GENITAL    OKGANS. 

The  spermatic  or  seminal  fluid  of  the  male  is  elaborated  in  two 
glands,  situated  in  the  scrotum,  called  the  testicles,  each  being 
furnished  with  an  excretory  duct,  the  vas  deferens,  which  trans- 
mits the  sperm  to  reservoirs  situated  on  the  bladder,  the  vesiculce 
seminales.  Here  the  sperm  accumulates,  and  is  expelled  by  the 
contractile   walls  of  the  vesiculee  during  the  act  of  copulation. 


SPERMATIC    CORD.  347 

through  the  ejaculatory  ducts  into  the  urethra,  which  is  commoi? 
to  the  urinary  and  generative  organs.  The  urethra  is  provided 
with  accessories,  the  'prostate  and  Cowper's  glands,  and  is  sup- 
ported by  an  erectile  tissue  which  forms  an  elongated  organ,  the 
penis. 

INGUINAL   CANALS. 

These  canals  afford  communication  between  the  abdominal 
and  scrotal  cavities.     They  have  been  described  (see  p.  203). 

SCROTUM — INGUINAL   FASCIA. 

This  is  a  sac  or  bag  which  contains  the  testicles,  situated 
between  the  thighs,  and  made  up  externally  of  a  layer  of  the 
common  integument,  continuous  with  that  of  the  abdomen,  flanks, 
and  sheath.  The  skin  covering  it  is  soft  and  thin,  generally 
black,  and  clothed  with  fine  downy  hairs ;  it  is  marked  mesially 
by  a  longitudinal  raphe,  indicating  its  division  into  right  and  left 
cavities.  Below  the  skin  is  a  thin  layer  of  muscular  and  elastic 
tissue  forming  the  proper  scrotal  tunic,  the  dartos,  which  sends 
in  a  fold  between  the  testes,  constituting  the  septum  scroti, 
and  corresponding  to  the  external  raphe.  The  dartos  is 
continuous  with  the  superficial  abdominal  fascia  or  elastic 
tunic.  Under  the  dartos  we  find  the  spermatic,  or  inter- 
columnar  fascia,  from  the  external  oblique  muscle,  attached 
to  the  margin  of  the  external  abdominal  ring,  and  passing 
down  over  the  cord.  Inside  this  is  the  cremasteric  fascia, 
an  expansion  of  the  cremaster  muscle,  arising  from  the  iliac 
fascia,  and  passing  through  the  inguinal  canal,  down  the  cord 
to  surround  the  testicle ;  this  fascia  forms  only  an  incomplete 
covering.  Still  deeper  seated  we  have  the  infundihuliform 
fascia,  which  is  an  extension  of  the  fascia  transversalis,  and  is 
funnel-shaped,  commencing  at  the  internal  abdominal  ring ;  it  is 
prolonged  as  a  sheath  over  the  cord  and  testicle,  and  is  connected 
with  their  serous  tunic. 

SPERMATIC   CORD. 

The  testicle  is  suspended  in  the  scrotum  by  the  spermatic 
cord,  a  structure  made  up  of  the  vas  deferens,  or  duct  of  the 
testis,  which  runs  along  its  posterior  edge,  with  various  blood- 
vessels,  nerves,  serous  membrane,  muscular   tissue,  and  fascia ; 


348 


SPLANCHNOLOGY. 


its  anterior  edge  contains  the  spermatic  artery  and  veins  ;  it 
extends  from  the  inguinal  canal  to  the  testicle,  certain  coverings 
being  common  to  it  and  the  latter. 

The  serous  covering  of  both  structures  is  continuous  with  the 
peritoneum,  and  consists  of  two  folds,  the  parietal  layer  being 
attached  to  the  infundibuliform  fascia,  the  visceral  layer  to  the 
duct,  vessels,  and  other  structures  which  help  to  form  the  cord. 
The  artery  of  the  cprd  supplies  the  spermatic  cord  with  blood. 


TESTICLE. 

The  male  g'enital  glands,  or  testicles,  are  two  oval,  compound 
tubular  glands,  situated  in  the  scrotum,  and  attached  superiorly 
to  the  spermatic  cord ;  their  long  axes  are 
placed  almost  horizontally  from  before  back- 
wards. In  foetal  life  they  are  at  first  situ- 
ated in  the  abdominal  cavity,  behind  the 
kidneys,Nand  above  the  peritoneum.  At  a 
certain  period,  they  descend  through  the 
inguinal  canals  into  the  scrotum.  In  their 
descent  each  is  guided  by  a  soft  cord,  the 
guhernaculum  testis  or  pilot,  which  at  first 
joins  them  to  the  abdominal  floor,  in  their 
descent  through  which  they,  and  the  sperm- 
atic cord,  carry  with  them  coverings  de- 
rived from  the  tissues  forming  the  abdo- 
minal parietes. 

Thus  from  without  inwards,  the  scrotum 
is  derived  from  the  skin  ;  the  dartos  from 
the  abdominal  tunic  ;  next  the  spermatic 
fascia,  very  rudimentary  in  the  horse,  and 
especially  about  the  testicle,  is  derived  from 
the  external  oblique ;  then  the  cremasteric 
fascia,  perhaps  from  the  internal  oblique ;  then  the  infundi- 
buliform fascia  from  the  fascia  transversalis ;  and  finally,  two 
serous  folds  from  the  peritoneum,  forming  a  shut  sac,  continuous 
in  the  domesticated  mammals  with  that  of  the  abdomen.  The 
remaining  coverings  of  the  testicle  are  peculiar  to  itself. 

The  outer  serous  covering  of  the  testicle  is  called  the  tunica 
vaginalis  rejlexa,  which  is  united  by  cellular  tissue  to  the  infundi- 
buliform  fascia;   the   inner,   the   tunica  vaginalis  propria,  is 


Fio.  124. 
Kxternal  view  of  right 
testicle  and  cord,  o,  Tes- 
ticle ;  6,  Globus  major  of 
epididymis;  6',Globlis  minor, 
c,  Fold  of  tunica  propria 
reflected  from  testicle  to  epi- 
didymis ;  d,  Spermatic  cord  ; 
«,  Vat;  deferens  ;  /,  Spermatic 
arter/. 


TESTICLE. 


349 


attached  to  the  outer  surface  of  the  subjacent  tunic — the  tunica 
albuginea,  dura  mater  testis,  or  proper  tunic,  which  is  a  dense 
fibrous  membrane  of  a  bluish -white  colour.  The  tunica  albu- 
ginea, after  surrounding  the  testicle,  is  reflected  into  its  substance, 
forming  a  septum  called  the  mediastinum  testis,  or  coryu^ 
Highmorianum,  from  which  originate  numerous  fibrous  cords, 
the  trabeculce  septulce,  which  terminate  on  the  inner  surface  of 
the  tunic,  dividing  the  organ  into  lobules.  Finally,  we  have  the 
most  internal  covering,  the  tunica  vasculosa,  or  pia  mater  testis, 
which  is  the  vascular  coat ;  it  lies  beneath 
the  preceding  one,  enclosing  the  testicle, 
and  supporting  the  vessels,  whose  branches 
ramify  on  the  mediastinum  testis  and  trabe- 
culae  septulse. 

.The  testicle  consists  of  a  soft  glandular 
substance  of  a  reddish-yellow  colour,  and  is 
divided  into  small  distinct  lobules,  varying 
in  number  from  200  to  300;  they  are  coni- 
cal in  shape,  having  their  base  towards  the 
surface,  and  consist  of  several  minute  con- 
voluted tubes,  the  tubuli  seminiferi,  which 
originate  as  loops  or  free  csecal  ends,  and 
are  most  convuluted  at  the  base  of  the  lobule, 
gradually  straightening  as  they  approach 
the  apex  at  the  mediastinum,  where  they 
unite  to  form  larger  tubes,  the  vasa  recta, 
which  enter  the  medis^stinum  and  terminate 
in  a  close  network  of  tubules,  the  rete  testis. 
These  pass  upwards  to  the  superior  extremity 
of  the  mediastinum,  where  they  terminate 
in  the  vasa  efferentia,  a  number  of  small 
ducts  which  perforate  the  tunica  albuginea; 
straight  at  first,  they  shortly  become  con- 
voluted, and  form  a  series  of  conical  masses, 
the  coni  vasculosi,  from  whose  bases  larger  tubes  issue,  the  whole 
forming  the  origin  of  the  epididymis. 


Fig.  125.* 

Diagramatic  view  of  the 
structure  of  the  testis.  1 1, 
Tunica  albuginea;  22,Medi- 
astinum  testis ;  33,Convol- 
uted  origins  of  semi  nif erous 
tubes  ;  4  4,  Vasa  recLa  ;  5, 
Rete  testis  ;  6,  Vasa  effer- 
entia ;  7,  Coni  vasculosi 
forming  the  globus  major ; 
8,  Body  of  epididymis  ;  9, 
«ilobus  minor  ;  10,  Vas 
deferens ;  11,  Vasculum 
aberrans. 


*  [Fig.  125  represents  the  structure  of  the  human  organ.  The  chief  differ- 
ence to  bear  in  mind  is  that  of  position,  the  long  axis  being  nearly  horizontal 
in  the  horse,  and  the  superior  extremity  in  the  cut  is  placed  anteriorly  in 
that  animal. — Ed.] 


350  SPLANCHNOLOGY, 


EPIDIDYMIS. 

The  epididymis  is  an  elongated  body  extending  along  the 
upper  border  of  the  testis,  and  covered  by  a  continuation  of  the 
tunica  vaginalis  propria.  It  consists  of  a  body,  a  head  or  globus 
major,  and  a  tail  or  globus  Tninor.  The  head,  situated  ante- 
riorly, is  closely  adherent  to  the  testicle  through  the  vasa  efferentia. 
The  body  is  free,  and  curved  to  the  shape  of  the  testicle,  to 
which  the  head  is  attached.  The  globus  minor,  posteriorly 
placed,  is  more  free  than  the  rest.  The  vasa  efferentia,  forming 
the  coni  vasculosi,  enter  the  globus  major,  and  successively  join 
at  irregular  distances  to  form  the  canal  of  the  epididymis ^  the 
convolutions  of  the  latter  forming  the  body  and  globus  minor. 
The  tubes  join  and  become  larger,  until  they  form  a  single  canal,, 
the  vas  deferens,  of  which  the  epididymis  may  be  regarded  as 
the  origin. 

VAS  DEFERENS. 

This  is  a  tube  with  firm  solid  walls,  which,  after  leaving  the 
globus  minor,  ascends  the  back  of  the  spermatic  cord  to  the 
inguinal  canal.  On  passing  through  the  internal  abdominal  ring, 
the  vas  deferens  leaves  the  cord  and  enters  the  pelvis,  passing  to 
the  antero- lateral  aspect  of  the  bladder,  where  the  obliterated 
umbilical  artery  winds  round  it;  it  then  becomes  dilated,  form- 
ing the  bulbous  portion ;  it  is  directed  backwards  and  inwards 
towards  the  neck  of  the  bladder ;  here  it  is  joined  by  the  duct  of 
the  vesicula  seminalis,  the  two  forming  the  ejaculatory  duct 
The  vas  deferens  thus  terminates  about  the  base  of  the  prostate 
gland.  A  long  narrow  tube,  the  vasculum  aberrans,  is  some- 
times found  leaving  the  lower  part  of  the  canal  of  the  epididymis, 
extending  a  short  way  up  the  back  of  the  testis,  between  it  and 
the  body  of  the  epididymis,  and  terminating  in  a  caecai  extrem- 
ity. The  vas  deferens  consists  of  three  coats — an  external  one  of 
connective  tissue,  a  middle  muscular  and  elastic,  and  an  internal 
mucous  coat,  lined  chiefly  with  columnar  epithelium. 

VESICULiE  SEMINALES. 

The  vesiculse  seminales  are  two  lobulated,  pear-shaped,  glandu- 
lar pouches,  situated  on  each  side  of  the  postero-superior  aspect 
of  the  bladder,  and  between  it  and  the   rectum.       Their  larger 


PROSTATE   GLAND.  351 

ends,  directed  forward  and  outward,  are  widely  separated,  their 
narrow  ones  almost  meet,  thus  forming  a  triangular  space  which 
corresponds  to  the  trigonus  vesicae  on  the  inside.  They  consist 
of  a  single  tube  which  terminates  in  a  blind  end,  and  gives  off 
several  branches  or  diverticula,  which  also  end  in  closed  extrem- 
ities. The  narrow  end  terminates  in  a  duct,  which  at  the  base 
of  the  prostate  is  joined  at  an  acute  angle  by  the  vas  deferens ; 
these  constitute  the  ejaculatory  duct.  The  vesicula  seminalis  is 
made  up  of  three  coats — an  external  fib/o-cellular,  a  central 
dense,  fibrous,  and  elastic,  said  to  contain  muscular  fibres,  and  an 
inner  pale  mucous  lining,  which  contains  tubular  glands,  secreting 
the  fluid  peculiar  to  the  cavity.  The  anterior  half  only  is 
covered  by  peritoneum,  a  fold  of  which  is  reflected  from  one 
vesicula  to  the  other. 

Blood  is  supplied  by  the  vesico-prostatic  arteries  ,  the  nerves 
come  from  the  pelvic  plexus.  They  are  seminal  receptacles, 
secreting  also  a  special  fluid  which  mixes  with  the  semen. 

EJACULATORY    DUCTS. 

These  ducts,  right  and  left,  are  formed  by  the  junction  of  the 
narrowed  extremities  of  the  vesiculse  seminales  and  the  vasa 
deferentia  just  at  the  base  of  the  prostate ;  they  pass  betweea 
its  middle  and  lateral  lobes,  terminating  in  the  urethra  by  twoi 
orifices,  one  on  each  side  of  an  opening  on  the  verumontanum, 
which  leads  to  a  sac  called  the  prostate  vesicle. 

The  prostate  vesicle,  sometimes  called  the  uterus  raasculinus, 
or  sinus  pocularis,  represents  in  the  male  the  uterus  and  vagina 
of  the  female.  It  is  a  canal  about  four  inches  in  length,  which 
ascends  in  the  folds  of  the  peritoneum  between  the  vasa 
deferentia ;  its  lower  end  is  situated  between  the  ejaculatory 
ducts.  It  opens  into  the  urethra,  on  the  verumontanum  between 
the  openings  of  the  ejaculatory  ducts,  sometimes  ending  in  one  of 
them.  It  is  lined  by  mucous  membrane  containing  tubular 
glands,  and  its  walls  are  of  a  fibre- muscular  nature. 

PROSTATE    GLAND. 

Situated  upon  and  partly  around  the  neck  of  the  bladder  and 
commencement  of  the  urethra,  this  organ,  a  compound  racemose 
gland,  is  connected  with  the  pelvis  and  the  rectum  by  the  pelvic 


352  SPLANCHNOLOGY. 

fascia.  It  varies  in  size,  and  consists  of  three  lobes;  a  middle 
and  two  lateral  ones  ;  the  middle  one  lies  on  the  posterior  part 
of  the  neck  of  the  bladder  and  the  superior  surface  of  the 
urethra;  in  old  animals  this  lobe  may  become  enlarged,  and 
pressing  on  the  urethra  cause  retention  of  urine.  It  is  enclosed 
in  a  dense  fibrous  capsule,  which  is  continuous  with  the  pelvic 
fascia.  It  is  pale,  reddish-grey,  and  very  friable,  consisting  of 
glandular  and  muscular  tissue,  containing  numerous  small 
follicular  pouches,  which  end  m  elongated  canals  ;  these  again 
unite  to  form  a  number  of  excretory  ducts,  which  open  in  a 
depression  called  the  prostatic  sinus,  situated  at  either  side  of  the 
verumontanum.  The  follicles  are  united  together  by  areolar 
tissue,  supported  by  prolongations  of  the  capsule.  The  canals 
and  the  follicles  are  lined  with  columnar  epithelium. 

The  prostate  gland  is  supplied  with  blood  by  the  vesico- 
prostatic  artery,  its  veins  forming  the  prostatic  plexus. 

cowper's  glands. 

Cowper's  glands,  called  also  in  veterinary  anatomy  the  lesser 
'prostates,  are  a  pair  of  small  bodies,  situated  on  either  side  of 
the  membranous  portion  of  the  urethra,  above  the  ischial  arch, 
covered  by  Wilson's  muscle.  They  are  of  a  reddish -yellow 
colour,  and  dense  m  their  structure,  cousisting  of  several  minute 
lobules  held  together  by  investing  cellular  tissue.  They  resemble 
the  prostate  gland  in  their  ultimate  structure,  being  compound 
racemose  or  aggregated  glands,  and  terminate  in  the  urethra  by 
s,  row  of  minute  openings  on  either  side. 

URETHRA. 

The  urethra  is  a  tube  which  extends  from  the  neck  of  the 
bladder  to  the  glans  penis  in  the  male,  and  from  the  bladder  to 
the  vulva  in  the  female.  In  the  latter  it  is  simply  an  excretory 
passage  for  the  urine,  but  m  the  male  it  transmits  also  the 
seminal  fluid.  It  consists  of  two  layers ;  an  internal  mucous 
one,  continuous  with  that  of  the  bladder  internally,  and  the 
covering  of  the  glans  penis  externally ;  and  an  external  layer 
consisting  of  fibrous  tissue,  with  muscular  fibres. 

It  is  divided  into  prostatic,  membranous,  and  spongy  portions. 
The  prostatic,  very  short,  is  the  most  dilatable  part  of  the  canal, 
commencing  at  the  neck  of  the  bladder.      It  passes  through  the 


PENIS.  353 

prostate  gland  below  its  middle  lobe.  The  membranous  division 
extends  from  the  prostatic  portion  to  the  ischial  arch,  and  is  the 
narrowest  part  of  the  canal,  being  surrounded  by  fibres  from  the 
retractor  ani  and  Wilson's  muscles;  it  is  sometimes  called  the 
muscular  division.  The  spongy  portion  extends  from  before  the 
ischial  arch  to  the  external  opening,  or  meatus  urinarius  ;  it  is 
narrow  in  the  middle,  but  dilated  at  either  end.  The  posterior 
dilatation  is  known  as  the  bulbous  portion.  Near  the  external 
orifice  the  canal  is  contracted,  but  on  reaching  the  glans  it  dilates 
and  forms  the  fossa  navicularis. 

As  the  urethra  leaves  the  neck  of  the  bladder  there  is  an 
elevation  of  its  mucous  membrane,  called  the  uvula  vesicae.  On 
laying  oven  the  urethra  from  the  neck  of  the  bladder,  the  first 
object  that  attracts  attention  is  an  elongated  ridge  on  the  roof  of 
the  prostatic  portion,  the  caput  gallinaginis,  verumontavum,  or 


Fig.  126. 
Bladder  and  pelvic  portion  of  urethra,  seen  from  below— the  laltci  being  laid 
open,  a,  Bulbous  portion  of  vas  deferens  ;  a'.  Fold  of  peritoneum  joining  vasa 
deferentia  .  b,  Vesicula  seminalis  ;  c.  Eight  lobe  of  prostate  gland  :  d.  Excretory 
canals  of  prostate ;  e,  Cowper's  gland  of  right  side  ;  /,  ^ts  excretory  orifices  ; 
g,  Verumontanum  with  openings  of  ejaculatory  ducts  ;  h.  Opening  of  uterus 
masculinus  ;  i,  Bladder ;  k,  Orifices  of  ureters  :  I,  Transverse  section  of  corpus 
cavernosum  ;  m,  Transverse  section  of  urethra. 

cjest  of  the  urethra,  which  contains  the  orifices  of  the  ejaculatory 
ducts  and  prostate  vesicle  ;  and  on  each  side  of  the  crest  is  a 
slight  groove,  the  prostatic  sinus,  into  which  the  prostatic 
secretion  is  poured  by  numerous  orifices.  About  the  commence- 
ment of  the  bulbous  portion,,  just  behind  the  membranous 
division,  are  the  openings  of  Cowper's  glands.  The  urethral 
mucous  membrane  is  furnished  with  numerous  depressions  or 
lacunae,  which  are  receptacles  of  mucus.  They  are  most  plentiful 
at  the  lower  part  of  the  spongy  portion,  and  in  the  fossa  navi- 
cularis is  a  very  large  one,  the  lacuna  magna. 

PENIS. 

The  penis  is  the  male  organ  of  copulation;    it  supports,  or 
rather  contains,  the  greater  part  of  the  urethra.     It  may  be  said 

2  a 


354  SPLANCHNOLOGY. 

to  consist  of  an  attached  and  a  free  portion ;  the  first  origi- 
nating at  the  ischial  arch,  in  the  pillars,  or  crura  penis,  and 
terminating  before  the  brim  of  the  pubis,  where  the  free  portion 
commences. 

The  substance  of  the  penis  is  formed  of  what  is  called  erectile 
tissue,  a  tissue  which,  under  certain  circumstances,  becomes 
enormously  distended  with  blood.  The  erectile  structures  are 
two  in  number,  the  corpus  cavemosum  and  the  corpus 
fipongiosum. 

The  corpus  cavemosum,  much  the  larger  of  these  structures, 
forms  the  superior  and  lateral  portions  of  the  penis ;  it  is  divided 
by  an  imperfect  fibrous  partition,  the  septum  pectiniforme,  into 
two  lateral  halves,  which  may  be  regarded  as  separate  corpora 
cavernosa.  This  septum  is  thick  and  complete  behind,  gradually 
thinning  as  it  approaches  the  free  extremity  of -the  penis,  where 
it  only  imperfectly  separates  the  halves.  It  consists  of  simple 
vertical  bands,  similar  to  the  teeth  of  a  comb,  extending  from 
above  downwards.  The  corpora  cavernosa  are  invested  by  a 
strong  elastic  fibrous  tunic,  whence  spring  trabeculse,  which 
divide  it  into  numerous  compartmente,  giving  it  a  cavernous 
appearance  ;  in  these  caverns  are  cells,  which  receive  the  blood 
during  erection  of  the  organ.  The  upper  surface  between  the 
cavernous  bodies  is  grooved  for  the  dorsal  vessels  ;  the  inferior 
aspect  is  also  grooved,  and  lodges  the  corpus  spongiosum.  The 
corpora  cavernosa  recede  from  each  other  posteriorly,  forming  the 
pillars,  or  crura  penis,  which  are  attached  to  the  ischial  arch, 
and  are  crossed  by  the  erectores  muscles,  which  blend  with 
them ;  anteriorly  they  terminate  in  blunt  points  behind  the.  gla.ns 
penis.  The  penis  is  attached  to  the  symphysis  pubis  by  two 
suspensory  ligaments,  which  spring  from  the  corpora  cavernosa. 

The  corpus  spongiosum  encloses  the  urethra,  is  situated  in  the 
inferior  groove  of  the  corpora  cavernosa,  and  surrounded  by  the 
accelerator  muscle.  It  commences  between  the  crura  by  an 
enlarged  portion,  the  bulb  of  the  penis,  and  passes  down  the 
groove  until  it  reaches  the  anterior  extremity,  where  it  expands 
to  form  the  glans.  The  spongiosum  is  enclosed  in  a  fibrous 
tunic,  similar  to,  but  more  delicate  than,  that  of  the  cavernosa. 

The  glans  forms  the  terminal  extremity  of  the  penis,  and  is  an 
enlargement  of  the  corpus  spongiosum.  At  its  apex  is  a  deep 
fossa,  in  the  centre  of  which  lies  the  meatus  urinarius,  bounded 
by  two  prominent  lips.       Ifc  terminates    posteriorly  by  a  con- 


MUSCLES  OF  THE  MALE  GENITAL  ORGANS.       355 

stricted  part,  the   cervix,   in   front    of   which  is  the   projecting 
-coro^aa  glandis. 

SHEATH. 

The  sheath  is  a  loose  process  of  integument,  which  invests  the 
free  portion  of  the  penis  ;  it  forms  a  corrugated  sac  extending 
from  the  scrotum,  with  which  it  is  continuous,  to  a  varying  dis- 
tance forwards.  Anteriorly  a  loose  double  fold  of  the  sheath 
projects,  covering  the  anterior  extremity  of  the  penis  completely 
when  quiescent ;  this  is  the  prepuce,  or  foreskin,  and  from  it  tho 
skin  is  continued  in  a  modified  form  over  the  glans,  which  it 
covers,  and  becomes  continuous  with  the  urethral  mucous  mem- 
brane ;  the  skin  around  the  prepuce  is  so  corrugated  as  to  admit 
of  the  erection  and  projection  of  the  penis,  during  which  the 
corrugations  become  effaced. 

The  inflected  fold  of  the  prepuce  is  void  of  hair,  and  resembles 
that  of  the  glans  in  structure,  being  intermediate  between  that  of 
skin  and  mucous  membrane  ;  opening  on  its  inner  surface  ?ire 
the  glandulce  odoriferce,  which  secrete  a  peculiar  odorous  matter, 
and  are  most  numerous  about  the  cervix.  The  sheath  is  sus- 
pended from  the  abdominal  walls  by  the  suspensory  ligaments, 
which  are  two  layers  of  yellow  elastic  tissue,  passing  from  the 
-abdominal  fascia  to  the  sides  of  the  sheath. 

MUSCLES   OF    THE   MALE    GENITAL    ORGANS. 
These  are  as  follows  :  — 

Cremaster.  I  Erector  penis. 

A.ccelerator  Urinje.         |  Retractor  penis. 

Wilson's  mvscle. 

Cremaster. — A  ribbon-shaped  muscle  arising  from  the  fascia 
covering  the  psoe  muscles ;  it  is  attached  by  cellular  tissue  to 
the  psoas  magnus  and  iliacus,  passes  through  the  inguinal  canal, 
and  is  distributed  over  the  infundibuliform  fascia ;  it  consists  of 
pale  delicate  fibres,  terminating  in  slender  tendinous  slips.  It 
raises  and  assists  in  suspending  the'  testicle. 

Accelerator  urince. — This  may  be  regarded  as  single  or  a  pair, 
consisting  of  transverse  fibres,  which  arise  from  the  ischial  arch, 
pass  along  the  under  surface  of  the  penis,  completely  investing 
the  urethra,  and  extend  as  far  forwards  as  the  glans,  the  fibres 
mutually  blending^  This  muscle  comprises  the  urethra,  and 
assists  in  the  discharge  of  urine  and  semen. 


356  SPLANCHNOLOGY. 

Erector  penifi. — This  is  a  somewhat  conical  muscle,  arising  from 
the  inferior  portion  of  the  tuberosity  of  the  ischium.  It  is 
inserted  to  the  penis,  and  is  a  retractor  and  levator  of  that  organ. 
Retractor  penis. — This  is  a  long,  flat  muscle,  arising  from, 
the  inferior  surface  of  the  sacrum  ;  it  descends  in  front  of  the 
sphincter  ani,  between  the  retractor  ani  and  the  walls  of  the 
rectum,  where  it  gives  off  numerous  short  bundles,  which  unite 
below  and  form  a  suspensoiy  ring  for  the  rectum.  It  now  passes 
along  the  ijiferior  surface  of  the  penis,  is  attached  to  the  acceler- 
ator urinae  by  cellular  tissue,  reaching  the  glans,  on  which  it  is 
lost.      It  retracts  the  penis  within  the  sheath. 

Wilson's  wiuscle. — A  muscle,  consisting  of  transverse  fibres, 
which  arise  from  the  lateral  walls  of  the  pelvis,  and  are  attached 
to  the  membranous  urethra,  embracing  Cowper's  glands.  It 
compresses  and  aids  in  the  discharge  of  the  glands,  and  contracts 
the  membranous  portions  of  the  urethra. 

Perineal  fascia. — This  is  situated  in  the  perineal  region,  and 
it  consists  of  two  layers,  a  superficial  and  a  deep.  The  former, 
which  is  fibro-elastic  in  its  structure,  lies  immediately  under  the 
skin,  and  is  connected  inferiorly  with  the  dartos  ;  it  extends 
upwards,  gradually  disappearing  as  it  nears  the  anus.  Internally 
this  layer  is  attached  to  the  deep  portion,  which  is  more  of  a 
white  fibrous  nature,  and  extends  from  the  rectum  downwards 
between  the  thighs,  becoming  gi'adually  lost  in  either  direction. 
It  is  related  with  the  erector,  and  accelerator  muscle,  and  also 
passes  between  the  former  and  the  adductor  magnus,  to  become 
attached  to  the  ischial  tuberosity. 

The  arteries  of  the  penis  are  the  external  and  internal  pudic, 
and  twigs  from  the  obturator.  The  nerves  come  from  the  internal 
pudic  and  sympathetic. 


SEMINAL    FLUID. 

The  secretion  of  the  male  genital  glands  is  a  viscid,  whitish, 
albuminous  fluid — the  sperm,  or  seminal  fluid,  which  contains 
the  spermatozoa,  microscopic  objects  consisting  each  of  an  ovoid 
head,  and  a  long  wavy  filamentous  tail.  They  possess  a  certain 
vibratory  motion,  and  have  the  power  of  penetrating  and  fertilis- 
ing the  female  ovum. 


FEMALE    GENITAL    ORGANS. 


357 


FEMALE    GENITAL    ORGANS. 

Adopting  a  similar  sequence  of  description  to  that  observed  in 
treating  of  the  male  organs,  we  note  that  the  female  genital 
glands  are  the  ovariex.  which  furnish  the  ovum  or  germ  of  the 
future  animal ;  the  ovum  is  conveyed  along  the  Fallopian  tube 
to  the  vterus,  a  cavity  in  which  it  becomes  impregnated  and 
developed.  The  vagina  is  a  tube  or  cavity  analogous  to  the 
urethra  in  the  male,  in  that  it  is  common  to  the  Urinary  and 
Genital  systems,  the  uteinis  opening  into  it  anteriorly,  and  the 
meatus  urinarius  being  situated  at  its  posterior  boundar}^      As 


Fig.  127. 
Female  urino-genital  organs  in  situ — the  abdomen  and  pelvis  being  opened  on  the  right  side  ; 
n,  Right  kidney  :  6,  Left  kidney :  c  e,  Ureters  ;  c'.  Eight  ureter  entering  bladder  ;  d,  Bladder  ; 
r.  Eiglit  lateral  ligament  of  the  bladder :  /,  lips  of  the  vxdva :  g,  Vagina  ;  h,  body  of  uterus ; 
Ji',  Its  rictht  cornu  ;  k",  Its  left  cornu  :  i.  Broad  ligameut  of  right,  and  i'.  Of  left  side  ;  k,  Fallopian 
tube  :  L,  Right  ovary  ;  m.  Left  ovary. 

the  neck  of  the  bladder  lies  immediately  under  the  vagina,  the 
urethra  in  the  female  is  exceedingly  short.  The  vulva  is  the 
external  orihce  of  the  vagina,  the  name  being  usually  held  to 
include  a  small  portion  of  the  cavity  within. 

To  these  organs  niay  be  added  structures  which  are  of  import- 
ance, since  they  form  the  most  prominent  characteristic  of  the 
mammalian  female — the  mammary  glands. 


OVARY. 
The  ovaries,  being  the  analogues  of  the  testes,  are  the  ultimate 
organs  of  generation  in  the  female.      They  are  ovoid,  similar  in 


358  SPLANCHNOLOGY. 

shape  to,  but  smaller  than  the  testicles,  and  are  situated  in  the 
sublumbar  region  of  the  abdomen,  being  suspended  from  its  roof, 
a  little  behind  the  kidneys ;  they  are  attached  anteriorly  to  the 
broad  ligament  of  the  uterus,  behind  and  below  the  Fallopian 
tubes.  In  addition  to  this  connection,  they  are  attached  at  their 
inner  end  to  the  uterus  by  a  muscular  cord,  the  ligaTnent  of  the 
ovary,  and  by  their  rounded  outer  end  to  the  fimbriated  extremity 
of  the  Fallopian  tube ;  they  are  also  supported  by  their  blood- 
vessels, which  enter  anteriorly  at  a  depression  called  the  hilus. 
An  ovary  possesses  an  external  serous  investment  from  the 
peritoneum  ;  and  beneath  is  the  dense  fibrous  tunica  albuginea, 
resembling  that  of  the  testicle,  which  encloses  the  stroma,  a  firm 
reddish-white  vascular  substance,  consisting  for  the  most  part  of 
connective  tissue,  and  apparently  continuous  with  the  external  coat. 
Within  are  numerous  small,  round  ovisacs  or  Graafian  vesicles, 
which  consist  of  two  coats,  an  external  vascular  and  an  inner  one, 
the  ovi-capsule,  lined  by  a  granular  and  so-called  epithelial  layer, 
the  membrana  granulosa.  The  granular  cells  of  which  this 
is  composed  accumulate  at  one  part  of  the  vesicle-  forming  the  layer 
{cumulus  jproUgerus),  in  which  is  embedded  a  small,  round  vesi- 
cular body,  the  true  ovum.  The  Graafian  vesicle  contains  a  fluid 
secreted  by  the  cells,  and  this  fluid  increases  in  quantity  as  the 
vesicle  develops,  and  at  the  same  time  the  latter  gradually 
approaches  the  surface  of  the  ovary,  the  intervening  stroma  be- 
coming absorbed.  Ultimately  the  wall  of  the  ovary  and  the 
Graafian  vesicle  give  way,  the  ovum  escapes  into  the  Fallopian 
tube,  and  is  by  it  conveyed  into  the  womb,  the  remains  of  the 
vesicle  being  converted  into  a  yellow  mass,  the  coitus  luteum, 
which  shortly  becomes  a  small  puckered  cicatrix. 

The  ovum  or  egg  is  in  the  higher  animals  microscopic,  being 
about  j-1^  of  an  inch  in  diameter.  It  is  a  cell,  possessing  all 
the  characteristics  of  such;  the  cell-wall  is  called  the  zona 
jjellucida,  vitelline  or  yelk  membrane,  which  contains  a  proto- 
plasm called  the  vitellus  or  yelk;  the  nucleus  of  the  cell  is  known 
as  the  germinal  vesicle,  the  nuoleolus  as  the  germinal  spot. 
The  arteries  are  derived  from  the  utero-ovarian. 


FALLOPLiN    TUBES. 

The  Fallopian  tubes,  oviducts,  or  uterine  trumpets,  are  two 
canals  which  convey  the  ova  from  the  ovaries  to  the  uterus.     They 


UTERUS.  359 

are  enclosed  in  the  free  borders  of  the  broad  ligament,  and  run  in 
&  serpentine  course  from  the  cul-de-sac  of  each  uterine  horn  to 
the  ovary.  The  canal  commences  at  the  horn  of  the  uterus  by  a 
very  minute  opening,  the  ostium  utennum,  gradually  enlarging 
into  a  trumpet-shaped  tube,  which  is  contracted  at  its  termina- 
tion, forming  a  small  round  orifice,  the  ostium  ahdominale,  which 
communicates  with  the  abdomen,  thus  forming  a  direct  com- 
munication between  the  mucous  membrane  of  the  uterus  and  the 
serous  membrane  of  the  abdomen.  The  free  extremity  of  the 
tube  terminates  in  a  series  of  irregular  jimhricB  or  fringes,  which 
are  arranged  in  a  circle  around  the  ostium  ahdominale.  One  of 
these  is  adherent  to  the  ovary,  and  along  it  is  a  fissure  continuous 
with  the  external  opening  of  the  tube ;  the  fimbriae  embrace  the 
•ovary  during  sexual,  excitement,  receiving  the  ovum  on  rupture 
of  the  ovisac,  and  conveying  it  into  the  Fallopian  tube.  The 
walls  of  these  tubes  consist  of  three  coats — an  external  or  serous 
one,  derived  from  the  peritoneum  ;  a  middle  muscular,  continuous 
with  the  uterine  muscular  wall,  and  consisting  of  an  external 
longitudinal,  and  an  internal  circular  layer  of  smooth  fibres ;  and 
an  internal  mucous  coat  thrown  into  longitudinal  folds,  and  con- 
tinuous with  that  of  the  uterus.  Ciliated  epithelium  lines  both 
the  tubes  and  the  inner  surface  of  the  fimbrise,  changing  to 
endothelium  as  the  mucous  and  serous  membranes  unite. 

Between  the  ovary  and  Fallopian  tube,  in  the  folds  of  the 
broad  ligament,  may  be  found  an  isolated  bunch  of  small  radi- 
ating tubes  termed  the  Par-ovarium. 

UTERUS. 

The  uterus,  or  womb,  is  a  musculo-membranous  sac  situated  in 
the  sublumbar  region  and  pelvic  cavity ;  it  consists  of  a  body  and 
two  cornua. 

The  body  is  cylindrical  and  somewhat  flattened ;  its  superior 
surface  contacts  the  rectum,  which  passes  between  the  horns,  while 
the  suspensory  or  broad  ligaments  are  attached  laterally  ;  tbe 
inferior  surface  and  borders  are  related  with  the  bladder  and 
intestinal  convolutions  :  the  anterior  extremity,  or  fundus,  is 
continuous  with  the  cornua ;  the  posterior  is  contiBuous  with  the 
vagina,  constituting  the  cervix,  or  neck,  which  is  thick,  round, 
and  projecting  in  the  virgin  animal.  In  the  centre  is  a 
transverse  aperture  or  fissure,  opening  into  the  vagina,  and  closed 


360 


SPLANCHNOLOGY. 


during  utero-gestation.  The  cylindrical  cornua  spring  from  th& 
anterior  extremity  of  the  body,  diverge  upwards  and  forwards^ 
together  presenting  an  inferior  free  convex  curvature  and  a 
superior  concave  one,  to  which  are  attached  the  suspensory 
ligaments.  Their  posterior  extremity  is  continuous  with  the 
body ;  while  the  anterior,  or  summit,  forms  a  cavity  turned 
upwards,  into  which  the  Fallopian  tube  enters. 

The  uterus  consists  of  three  coats  ;  an  external  serous,  central 
muscular,  and  internal  mucous.      The  serous  coat,  a  reflection  of 


Fio.  128. 

Female  generative  organs  partly  laid  open— seen  from  above,  a  a,  Lips  of  vulva  divided  at  the 
superior  commissure;  b,  Clitoris;  c,  Prepuce;  d  d,  Vagina  laid  open;  e,  Bladder;  e',  Meatus 
urinarius  ;  /,  Its  valve,  of  mucous  membrane  ;  fir,  Neck  of  the  uterus  ;  ff'  flf'.  Body  of  uterus  opened ; 
h,  Eight  cornu  opened  ;  i,  Fallopian  tube ;  k.  Ovary. 


the  peritoneum,  covers  the  body  and  horns,  forms  the  hroad,  or 
suspensory  ligaments,  and  is  reflected  on  to  the  bladder,  rectum, 
vagina,  and  walls  of  the  pelvic  cavity,  forming  the  ligaments. 
The  broad  ligaments  pass  from  either  side  of  the  uterus  to  the 
pelvic  walls,  forming  a  septum  across,  and  dividing  the  pelvis 
into  two  portions,  the  inferior  containing  the  bladder,  vagina, 
and  urethra ;  the  superior  the  rectum.  Two  peritoneal  folds, 
the  superior,  or  recto-uterine  ligament,  unite  the  uterus  to  the 


VULVA.  361 

rectum  ;  and  two  pass  from  the  uterus  to  the  bladder,  the 
inferior,  or  vesico-uterine  ligament.  Two  fibrous  cords,  the 
round  ligaments,  arise  from  the  upper  angle  of  the  uterus, 
proceed  to  the  internal  abdominal  rings  through  the  inguinal 
■canals,  and  are  lost  in  front  of  the  symphysis  pubis.  The 
arteries  are  the  uterine  and  utero-ovarian,  with  corresponding 
veins.  After  once  bearing  young  these  vessels  are  very  large. 
The  nerves  are  from  the  mesenteric  and  pelvic  plexus. 

The  muscular  coat  consists  of  two  layers  analogous  to  those  of 
the  intestine,  longitudinal  and  transverse.  The  external  layer  is 
thin,  and  encircles  the  anterior  part  of  the  body,  cornua,  and  Fal- 
lopian tubes,  sending  fasciculi  between  the  folds  of  the  broad 
ligament.  The  muscular  coat  is  better  developed  in  the  gravid 
uterus.  The  mucous  coat  is  thin,  smooth,  and  closely  adherent 
to  the  muscular  one,  more  especially  in  the  body ;  it  is  pale 
reddish- white,  clothed  with  ciliated  epithelium,  and  furnished 
"with  numerous  mucous  follicles  and  glands  peculiar  to  the  organ 
— the  utricular  glands.  A  network  of  rugae  exists,  termed  the 
urbor  vitce  uterinus.  The  uterus  has  three  openings,  one, 
the  ostium  uterinum,  at  the  end  of  each  horn,  for  the  Fallopian 
tube,  and  one,  the  ostium  internum,  leading  through  the  cervix, 
about  which  the  mucous  glands  are  vesicular  and  prominent,  and 
known  as  the  Nahothian  Glands  {OvuU    Kahothi). 

VAGINA. 

The  vagina  is  the  cylindroid  membranous  canal  leading  from 
the  vulva  to  the  uterus,  and  also  situated  between  the  rectum 
and  the  bladder.  It  consists  of  two  membranes ;  an  inner 
mucous  and  an  outer  muscular,  invested  by  a  reflection  of  the 
pelvic  fascia.  Constricted  at  its  origin,  the  vagina  widens  at  its 
inner  portion,  and  surrounds  the  neck  of  the  uterus.  The 
mucous  coat,  clothed  with  numerous  papillae,  and  studded  with 
follicles,  presents  a  number  of  longitudinal  rugae,  which  abound 
at  the  constricted  opening,  and  which  facilitate  dilatation  during 
parturition.  Blood  is  supplied  by  the  internal  pudic  artery ; 
nerves  by  the  pelvic  plexus. 

The  vagina  is  the  chief  female  organ  of  coition. 

VULVA. 

This,  the  external  orifice  of  the  urino-geuital  system,  is 
situated   in   the   perineal   region,   immediately   below    the   anus; 


362  SPLANCHNOLOGY. 

the  opening  appears  as  a  long  verticle  ovoid  slit,  the  fissura 
magna,  presenting  two  lips  and  two  commissures.  The  labia^ 
or  lips,  are  formed  by  an  external  soft  unctuous  layer  of  skin, 
destitute  of  hair,  but  rich  in  pigment,  and  an  inner  one  of 
mucous  membrane ;  between  these  is  a  quantity  of  fat  and 
areolar  tissue,  most  abundant  in  the  young  animal,  and  the 
erectile  vaginal  bulb,  divided  into  two  branches,  which  leave  the 
clitoris,  and  pass  along  the  sides  of  the  vulva,  terminating  in 
round  lobes  ;  this  structure  is  filled  with  blood  during  copulation, 
rendering  co-aptation  very  complete.  The  superior  commissure 
is  very  acute,  and  reaches  almost  to  the  anus  ;  the  space  between 
the  two  is  the  perineum.  The  .inferior  commissure  is  obtuse 
and  rounded. 

In  the  interior  of  the  vulva,  and  in  a  depression  on  its  floor 
called  the  fossa  navicularis,  lies  the  clitoris,  which  originates 
by  two  crura  from  the  ischial  arch,  and  is  attached  to  the 
symphysis  by  a  suspensory  ligament.  The  clitoris  passes  back- 
wards, jutting  towards  the  inferior  commissure,  its  free  extremity 
being  lodged  in  the  fossa  navicularis,  and  enveloped  by  a  mucous 
covering,  the  prepuce  of  the  clitoris.  The  structure  of  the 
clitoris  resembles  that  of  the  corpora  cavernosa  of  the  male  ;  and, 
having  a  fibrous  capsule,  erectile  tissue,  and  cavernous  vessels,  it 
becomes  erect  during  copulation. 

The  external  orifice  of  the  urethra,  the  meatus  urinarius, 
opens  on  the  inferior  surface  of  the  vulva,  about  four  inches  from 
its  external  opening ;  it  is  larger  than  the  male  opening,  and 
surmounted  by  a  fold  of  mucous  membrane,  which  acts  as  a 
valve.  The  hymen  is  a  thin  semilunar  fold  of  mucous  membrane, 
which  separates,  usually  imperfectly,  the  vulva  from  the  vagina, 
lying  immediately  before  the  meatus ;  it  is  ruptured  during  the 
first  act  of  copulation,  which  gives  rise  to  a  number  of  small 
round  elevations  surrounding  the  entrance  of  the  vagina,  called 
the  carunculoB  myrtiformes. 

The  mucous  membrane  lining  the  vulva  is  pale  rose-coloured, 
and  covered  with  mucous  follicles,  which  are  more  numerous  near 
the  opening  of  the  urethra,  and  sebaceous  glands,  the  glandulce 
odoriferce,  which  secrete  an  odorous  unctuous  substance,  and  are 
found  for  the  most  part  under  the  prepuce  of  the  clitoris  and  on 
the  labia. 


MAMMARY    GLANDS.  363 


MUSCLES   OP   THE   FEMALE    GENITAL   SYSTEM. 

Erectorea  clitoridis. — A  pair  of  very  small  muscles  analogous 
to  the  erectores  penis  of  the  male.  Tbey  arise  from  the  ischial 
arch,  and  are  attached  to  and  closely  associated  with  the  crura  of 
the  clitoris. 

Constrictor  vulvae  anterior. — ^^This  is  considered  the  homo- 
logue  of  Wilson's  muscle  ;  its  fibres  are  arciform,  and  embrace 
the  posterior  part  of  the  vagina,  below  and  at  the  sides,  its 
aponeurosis  being  reflected  on  the  sides  of  the  rectum. 

Constrictor  vulvae  posterior. — Included  in  the  labia  of  the 
vulva,  and  disposed  as  a  sphincter,  this  muscle  is  attached  to  the 
skin  by  cellular  tissue.  It  is  attached  to  the  sphincter  ani  above, 
and  also  to  the  sacrum  by  the  suspensory  ligaments.  It  is  the 
analogue  of  the  sphincter  vaginae  in  the  human  subject. 

Suspensory  ligaments. — Attached  to  the  sacrum  above,  and 
uniting  under  the  rectum,  these  structures  resemble  the  retractor 
penis  of  the  male.  They  again  separate  and  become  lost  laterally 
in  the  posterior  constrictor  muscle. 

From  the  above  descriptions  it  will  be  apparent  that  in  the 
male  animal  the  female  generative  organs  are  indicated,  as  are 
the  male  organs  in  the  female.  Thus  in  the  male  the  sinus 
pocularis  represents  an  undeveloped  uterus ;  and  in  the  female 
the  clitoris  a  rudimentary  penis.  This  points  to  the  fact  that  in 
early  foetal  life  there  is  no  distinction  of  sex,  each  animal  having 
rudimentary  male  and  female  generative  organs ;  only  one  of 
these  becomes  developed,  thus  determining  the  sex  of  the  animal. 
Should  both  systems  of  organs  in  the  same  animal  become  more 
or  less  developed,  but  neither  of  them  perfectly  so,  the  animal  is 
said  to  be  hermaphrodite. 

MAMMARY    GLANDS. 

The  mammae,  or  mammary  glands,  are  characteristic  of  the 
highest  class  of  the  animal  kingdom — the  mammalia.  They  are 
compound  racemose  glands,  which  secrete  milk  for  the  nourish- 
ment of  the  recently-born  animal.  In  the  young  female,  as  in 
the  male,  they  are  rudimentary,  becoming  developed  in  the 
former  at  puberty,  or  when  the  female -is  fit  for  reproduction. 
During  utero-gestation  they  gradually  enlarge,  and  at  parturi- 


364  SPLANCHNOLOGY. 

tion  reach  their  greatest  activity.  When  the  period  of  suckling 
terminates,  they  shrink,  returning  almost  to  their  original  state. 

In  the  mare,  these  glands  are  two  in  number,  and  placed,  side 
by  side,  in  the  inguinal  region,  between  the  thighs  and  under 
the  pubis,  having  the  same  relative  position  in  the  female  as  the 
scrotum  has  in  the  male.  In  full  activity,  they  present  two 
hemispherical  masses,  separated  by  a  shallow  fissure,  each  half 
presenting  in  its  centre  a  nipple,  teat,  or  mammary  process, 
pierced  at  its  free  extremity  by  numerous  orifices  for  the  passage 
of  the  milk  The  mammae  are  supported  by  an  outer  covering, 
a  continuation  of  the  common  integument,  and  by  numerous 
short  elastic  plates,  similar  to  the  suspensory  ligament  of  the 
male  sheath,  derived  from  the  elastic  abdominal  fascia.  The 
outer  tunic  of  integument  is  soft,  black,  and  covered  with  fine 
downy  hair,  which  disappears  towards  the  teat.  Below  this  is  a 
thin  elastic  covering  which  blends  with  the  elastic  plates  descend- 
ing from  the  abdominal  fascia.  Besides  supporting  the  gland,  it 
sends  into  its  substance  several  prolongations,  which  form 
partitions  between  the  principal  lobes. 

The  interior  of  a  mamma  is  made  up  of  yellow  glandular 
tissue,  consisting  of  numerous  lobes,  united  by  cellular  tissue. 
Each  of  these  is  again  made  up  of  small  lobules,  composed  of 
minute  ducts  and  numerous  small  cells,  or  acini,  in  which  the 
milk  is  secreted  and  conveyed  to  the  ducts,  which  unite  to  form 
a  common  excretory  duct  for  each  lobe — the  ductus  lactiferus,  or 
galactophorus.  These  increase  in  size,  and  by  repeated  union 
converge  to  the  centre  of  the  gland,  where  they  terminate  in 
dilated  cavities — the  lactiferous  sinuses,  which  vary  in  number, 
and  freely  communicate  with  each  other.  From  these  proceed  a 
number  of  distinct  canals,  which  run  in  a  straight  course  to  the 
free  extremity  of  the  teat,  where  they  terminate  in  a  cribriform 
manner,  and  by  contracted  orifices.  The  internal  surface  of  this 
excretory  apparatus  is  lined  by  a  fine  mucous  membrane,  clothed 
with  columnar  epithelium. 

The  mucous  membrane  of  the  ducts  is  surrounded  by  a  layer 
of  muscular  fibre,  which  acts  involuntarily  as  a  sphincter,  and 
retains  the  milk,  being  assisted  by  a  thin  layer  surrounding  the 
free  end  of  the  teat.  The  teat  is  covered  with  skin,  devoid  of 
hair,  and  at  its  base  is  encircled  by  certain  glands,  secreting  a 
sebaceous  lubricating  matter  which  protects  the  teat  during  the 
suckling  of  the  young,  and  prevents  plugging  of  the  orifices  by 


BUMINANTIA— DIGESTIVE    SYSTEM.  565 

coagulation  of  the  milk.  The  mammse  are  supplied  with  blood 
Tjy  the  mammary  arteries,  vessels  corresponding  to  the  external 
pudics  of  the  male. 


COMPARATIVE   SPLANCHNOLOGY. 

Although  the  viscera  of  the  domestic  animals  are  constructed  on  the  same 
general  plan,  still  there  are  many  important  deviations  in  form  and  arrange- 
ment from  those  of  the  typical  animal.  The  more  important  of  these  features 
we  now  proceed  briefly  to  consider. 

RUMINANTIA. 

DIGESTIVE  SYSTEM. 

The  lips  of  the  ox  are  thick  and  rigid,  and  having  very  little  mobility,  are 
only  indirectly  prehensile.  A  large  part  of  the  outer  centre  of  the  upper  lip 
is  devoid  of  hair,  prolonged  between  the  nasal  openings,  and  constitutes  the 
muzzle.  It  varies  in  colour  with  the  animal,  but  in  health  is  always  moist. 
It  is  covered  with  papillae  and  the  orifices  of  the  ducts  of  subcutaneous  glands, 
which  moisten  the  part  with  their  secretion.  The  lips  of  the  smaller  ruminants 
are  thin,  and,  being  very  mobile,  are  agents  of  prehension  ;  the  superior  one 
is  divided  in  front  by  a  median  fissure. 

The  cheeks  of  ruminants  present  on  their  inner  surface,  between  the  com- 
missure of  the  lip  and  the  first  molar  tooth,  numerous  large,  long,  conical 
papillae  which  point  backwards.  Posteriorly  a  row  of  the  same  rims  along  the 
level  of  the  upper  molars.     Small  round  papillae  are  also  present. 

The  hard  palate  is  large,  its  posterior  third  being  smooth  ;  the  anterior  two- 
thirds  are  covered  with  transverse  bars,  which  do  not  form  arches,  but  are 
denticulated,  the  ridges  projecting  backwards.  Behind  the  pad  of  cartilage 
which  replaces  the  upper  incisors  there  is  a  mark  resembling  a  letter  T  in  the 
middle  line,  with  the  normal  directed  backwards,  and  at  each  extremity  of  the 
transverse  line  is  the  buccal  opening  of  Jacobson's  canal. 

The  soft  palate  is  not  so  complete  and  pendulous  as  in  the  horse.  The 
isthmus  faucium  is  always  open,  thus  permitting  the  animal  to  breathe  through 
the  mouth,  and  allowing  the  upward  passage  of  food.  Some  authorities  hold 
that  the  tonsils  are  present  in  ruminants. 

The  tongue  of  the  ox  being  prehensile,. its  muscles  are  well  developed,  and  it 
possesses  great  mobility.  It  is  much  rougher,  shorter,  and  thicker  than  in  the 
horse,  and  pointed  at  the  tip.  The  papillae  are  better  developed,  the  filiform 
being  very  large  and  numerous  near  the  apex.  The  circumvallatae  are  arranged 
in  two  rows,  one  on  each  side  of  the  base,  and  number  about  ten  on  either 
side.  Between  the  lower  border  of  the  tongue  and  sides  of  the  lower  dental 
arch  is  a  row  of  conical  papillae,  similar  to  those  on  the  cheek.  The  tongue  of 
the  smaller  ruminants  is  very  delicate. 


366  COMPARATIVE  SPLANCHNOLOGY. 

The  parotid  gland  is  small  and  red  ;  the  duct  follows  a  similar  course  to  that 
of  the  horse,  but  enters  the  mouth  much  more  posteriorly  ;  in  small  ruminants 
it  crosses  the  masseter  externally.  The  submaxillary  gland  is  very  large  and 
yellow  in  colour.  The  canal  of  Wharton  opens  close  to  the  incisors,  the  papillae 
bein"  lodged  in  an  elliptical  fossa.  The  sublingual  gland  is  divided  into  two 
portions,  the  posterior  opening  by  a  sipgle  duct  (the  duct  of  Bartholini)  close 
behind  Wharton's,  the  anterior  by  a  row  of  ducts  as  in  the  horse. 

The  dentition  of  the  ruminant  is  characteristic.  With  the  exception  of  the 
camel  and  llama,  which  are  not  usually  domesticated  in  Europe,  the  ruminant 
has  neither  incisor  nor  canine  teeth  in  the  upper  jaw,  thei  former  being  replaced 
by  a  thick  cartilaginous  pad,  covered  by  the  mucous  membrane  of  the  hard 
palate,  forming  a  point  d'dppui  for  the  lower  incisors  to  press  against  in  cropping 
grass,  &c.  In  the  lower  jaw  there  are  six  incisor  teeth,  and  two  canines  ;  the 
latter  closely  resembling  the  former  in  shape,  and  being  situated  immediately 
behind  them,  indeed  it  is  customary  to  describe  the  incisors  as  eight  in  number; 
it  signifies  little  which  view  is  taken.  These  teeth  are  chisel-shaped,  rather 
like  the  human  incisors,  but  with  a  curved  contour,  convex  anteriorly,  and 
concave  behind,  the  whole  of  the  crown  being  covered  with  enamel ;  the  neck 
is  small  and  constricted,  and  the  teeth  are  arranged  in  the  jaw  in  an  almost 
horizontal  position,  forming  a  radiating,  or  fan-like  series.  They  are  not 
firmly  fixed  in  the  alveoli,  but  have  a  certain  degree  of  mobility,  thus  prevent- 
ing injury  to  the  cartilaginous  pad  above.  The  molars  have  compound  tables 
like  those  of  the  horse,  but  the  teeth  are  much  smaller  and  more  cuboid  in 
shape. 

The  dental  formula  of  the  domesticated  ruminant  is  as  follows  : 

.Or-0      0-0  3-3        3-3 

i.  r_r,  c.  ^—^,  p.m.  r__?,  m.  ^— ?  =.32 
3-3      l-l'^      3-3        3-3 

That  of  the  camel  is  : — 

3-3'      1-1'"^       2-2         3-3 

(Thomes.) 

The  pharynx  is  large,  but  the  muscles  composing  it  are  less  distinctly 
separable.  The  oesophagus  is  well  developed,  and  its  muscular  walls  are  red 
throughout.  It  joins  the  stomach  by  expanding,  so  that  its  termination  is 
funnel-shaped.  The  muscular  fibres  induce  both  a  downward  or  peristaltic, 
and  an  upward  or  anti-peristaltic  motion. 

Stomach. 
The  stomach  of  the  ruminant  is  a  very  complex  organ,  consisting  of  four 
compartments,  which  vary  in  size,  form,  and  in  the  disposition  of  their 
mucous  coats.  The  first  compartment  is  the  rumen,  or  paunch ;  the  second 
the  reticulum,  or  honeycomb  ;  the  third  the  omasum,  psalterium,  or  many- 
plies  ;  the  fourth  the  abomasum,  or  true  digestive  cavity.  The  first  three 
have  little  to  do  with  the  essential  process  of  digestion,  being  principally 
concerned  in  macerating  and  preparing  the  food,  and  are  analogous  to,  the 
cardiac  portion  of  the  stomach  of  the  horse.  The  runun  in  the  adult  is 
very  large,  occupying  about  three-fourths  of  the  abdomen.     It  is  situated 


RUMINANTIA STOMACH. 


367 


oa  the  left  side,  incliuing  obliquely  downwards  from  left  to  right,  and 
elongated  from  before  backwards.  The  surface  is  smooth,  and  divided  into 
two  lateral  regions  or  hemispheres  by  slight  grooves,  which  deepen  towards 
the  extremities.  The  sides  are  smooth,  thick,  and  rounded ;  the  extremities 
are  divided  by  a  deep  fissure  into  two  lobes,  the  anterior  being  concealed. 
These  two  fissures,  continued  by  the  grooves,  divide  the  rumen  into  a  right  and 


Fi(i.  129. 
Stomach  of  an  Ox  inflated— viewed  from  the  right  side.  A,  Rumen  ;  a.  Left  sac  ;  a',  Its  anterior 
extremity ;  a",  Left  conical  sac  ;  b,  Right  sac  ;  b'.  Its  anterior  extremity  ;  b",  Right  conical  sac  ; 
c,  Superior  border  of  rumen  ;  d.  Its  inferior  border  ;  e  e,  Longitudinal  groove  ;  yr,  ffisophagus  ; 
'/,  Its  dilated  extremity  entering  rumen  ;  h,  Spleen  ;  B,  Reticulum  ;  i,  Its  greater  curvature  ;  k,  Its 
I  left  extremity;  I,  Its  right  extremity;  C,  Psalterium  ;  m,  Its  greater  curvature;  n,  Its  lesser 
'curvature;  o,  Its  anterior  extremity;  p,  Its  posterior  extremity;  D,  Abomasum  ;  q.  Its  greater 
curvature  ;  r.  Its  lesser  curvature  ;  s,  Its  anterior  extremity  ;  t.  Its  posterior  extremity  ;  u,  Pylor- 
us ;  r,  Duodenum. 


left  sac,  which  is  most  manifest  in  the  anterior.  The  right  sac  is  the  shortest, 
being  covered  in  the  major  part  by  the  peritoneal  omentum  ;  the  left  is  pro- 
longed beyond,  and  at  either  extremity  curved  on  the  right,  receiving  super- 
jiorly  the  insertion  of  the  oesophagus,  and  is  also  continuous  anteriorly  with 


Ob 8  COMPARATIVE    SPLANCHNOLOGY. 

the  second  compartment.  The  anterior  extremity  is  bounded  by  the  second 
and  third  compartments,  and  lies  near  the  diaphragm  ;  the  posterior  occupies 
the  entrance  of  the  pehnc  cavity,  where  it  contacts  the  urino-genital  organs. 
In  the  female,  the  uterus  is  prolonged  over  this  surface. 

The  superior  surface  is  related  with  the  intestines  ;  the  inferior  rests  upon 
the  abdominal  floor  ;  the  left  side,  to  which  the  spleen  is  united,  is  in  contact 
with,  and  attached  by  cellular  tissiie  to*  the  abdominal  wall  in  the  lumbar 
region.  The  right  side  is  related  with  the  fourth  compartment  in  the  right 
hypochondriac  and  lumbar  regions,  and  is  surrounded  by  convolutions  of  the 
intestines. 

The  interior  of  the  rumen  is  incompletely  divided  into  four  sacs  by  fleshy 
pillars.  The  principal  ones  are  the  anterior  and  posterior,  which  correspond 
to  the  anterior  and  posterior  fissures ;  processes  from  these  run  transversely, 
corresponding  to  constrictions  on  the  outer  surface  ;  thus  anteriorly  there  are 
formed  the  right  and  left  sacs  ;  posteriorly  the  right  and  left  conical  sacs. 

The  rumen,  like  the  other  compartments,  consists  of  three  coats  ;  an  external 


Fia.  130. 
stomach  of  a  Sheep  seen  from  the  left  side— the  last  three  compart- 
ments are  laid  open  and  reflected  forwards,  as,  CEsophagus  ;  Ru., 
Rumen;  Rd.,  Keticulum :  Ps.,  Psalterium  ;  A.,  Abomasum  ;  Du., 
Duodenum.  The  fiesophageal  canal  is  seen  traversing  the  lesser  curva- 
ture of  the  reticulum. 

serous,  a  continuation  of  the  peritoneum,  which  envelops  the  entire  organ, 
excepting  where  it  contacts  the  lumbar  region  ;  the  thick  muscular  middle 
coat  is  an  extension  from  the  a^sophageal  fibres  ;  the  internal  mucoiis  coat  is 
cuticular,  papillated  and  covered  by  thick  epithelium.  The  papillae  are  foliate 
or  leaf-like,  conical,  and  fungiform,  the  first  variety  being  by  far  the  most 
numerous.  The  rumen  has  two  openings,  both  of  which  enter  the  anterior 
extremity  of  the  left  sac  :  the  superior,  or  oesophageal,  which  opening  is  pro- 
longed over  the  small  curvature  of  the  second  compartment  by  the  (Esophageal 
canal,  shortly  to  be  described ;  the  inferior,  large  and  communicating  with  the 
reticulum,  is  circumscribed  laterally  and  below  by  the  free  border  of  a  kind 
of  valve,  formed  by  the  walls  of  the  rumen,  along  with  the  cells  of  the  second 
compartment. 

The  second  compartment,  or  reticulum,  the  smallest  of  the  four,  is  slightly 
Tsent  upon  itself,  and  placed  transversely  between  the  posterior  surface  of  the 
diaphragm  and  the  anterior  extremity  of  the  left  sac  of  the  rumen.  The  anterior 
surface  adheres  to  the  centre  of  the  diaphragm  by  cellular  tissue  ;  the  posterior 


RUMINANTIA DIGESTIVE    SYSTEM. 


369 


is  united  to  the  anterior  extremity  of  the  rumen.  The  inferior  convex  curvature 
occupies  the  epigastric  region; 
the  superior  concave  one  is 
pariially  related  with  the  small 
curvature  of  the  third  com- 
partment. The  left  extremity 
in  separated  from  the  rumen 
by  a  fissure,  in  which  runs  the 
inferior  artery  of  the  reticu- 
1  m  The  right  forms  a  roimd 
cul-de-sac,  and  is  related  with 
the  base  of  the  fourth  com- 
partment. The  internal  sur- 
face of  the  reticulum  is  divided 
into  polyhedral  alveoli  or  cells, 
by  folds  of  the  mucous  mem- 
brane. These  folds  are  stud- 
ded with  papillae,  and  serrated 
at  their  edges  ;  in  the  alveoli 
are  secondary  ones,  where 
mucous  follicles  open.  The 
reticulum  coinmunicates  with 
the  left  sac  of  the  rumen,  the 
cesophagus,  and  third  com- 
partment. The  communica- 
tion with  the  two  latter  is  by 
the  oesophageal  canal,  a  con- 
tinuation of  ihe  oesophagus, 
which  commences  at  the  car- 
diac oriiice,  passes  along  the 
roof  of  the  retictdum,  and 
enters  the  third  compartment 
by  a  circular  opening.  Its 
sides  consist  of  two  movable 
lips,  the  (esophageal  pillars, 
which  are  continuous  with  the 
muscular  wall  of  the  oesopha- 
gus, and  are  attached  by  one 
border  to  the  superior  wall  of 
the  reticulum,  the  other  being 
free.  The  latter  get  gradually 
thicker  and  more  projecting 
as  they  reach  the  opening  of 
the  third  compartment.  At 
the  entrance  into  the  rumen 
i6  a  sort  of  valve,  formed  by 
the  attachment  of  the  piUars  to  its  walls 


Fio.  131. 
Compartments  of  a  Ruminant  Stomach,  laid  open.  A, 
Kumen— a,  a,  a,  a,  Pillars ;  6,  6,  Papillas  ;  c,  (Esophageal 
orifice.  B,  Eeticulum — a,  a,  Alveoli ;  6,  CEsophageal 
canal.  C,  Psalterium— a,  Hooked  papillae;  6,  Valve  at 
orifice  leading  to  abomasum  ;  c,  d,  e,  f,  Leaves  graduated 
from  large  to  small.  X»,  Abomasum— a,  a,  Polds  of 
mucous  membrane  ;  b,  Pyloric  orifice ;  c,  Duodenum. 


The  mucous  membrane  of  thia 

2b 


370  COMPARATIVE  SPLANCHNOLOGY. 

canal  is  wrinkled  on  its  free  surface,  but  on  the  interior  resembles  that  of  the 
oesophagus,  being  white,  and  longitudinally  folded.  At  its  opening  into  the 
third  compartment  are  a  number  of  conical  papillae.  Transverse  and  longitu- 
dinal muscular  fibres  control  the  canal  ;  the  longitudinal  fibres,  by  drawing 
the  lips  of  the  pillars  together,  form  a  channel  leading  from  the  oesophagus 
into  the  third  compartment,  thus  eflfectually  closing  the  openings  into  the 
rumen  and  reticulum. 

The  third  com-psLTtment ,  psalterium  or  omasum,  is  situated  at  the  anterior 
extremity  of  the  right  sac  of  the  rumen.  When  full,  it  is  ovoid,  slightly  curved, 
and  depressed  from  above  downwards.  The  anterior  surface  is  in  relation  with 
and  attached  to  the  diaphragm  by  cellular  tissue,  while  the  posterior  is  related 
with  the  rumen.  The  greater  or  convex  curvature  is  turned  upwards,  and 
fixed  to  the  posterior  fissure  of  the  liver  by  a  fold  of  peritoneum,  which  is  con- 
tinued on  to  the  lesser  curvature  of  the  fourth  compartment,  and  thence  to 
the  duodenum.  The  lesser  curvature  looks  downwards,  and  is  related  with 
the  reticulum.  The  left  extremity  is  constricted,  forming  the  neck,  by  which 
it  communicates  with  the  reticulum.  The  right  extremity  is  continuous  with 
the  base  of  the  fourth  compartment,  from  which  it  is  separated  by  a  constric- 
tion similar  to,  but  less  marked  than,  the  neck. 

The  interior  presents  two  openings,  one  of  which  communicates  with  the 
second,  the  other  with  the  fourth  compartment.  It  is  filled  with  leaves  or 
folds  of  mucous  membrane,  which  follow  the  long  axis  of  the  organ.  They  are 
unequally  developed,  and  attached  by  one  border  to  the  great  curvature  of  the 
cavityi  while  the  other,  free  and  concave,  is  turned  towards  the  lesser  curva- 
ture. The  cavity  being  ovoid,  the  central  leaves  are  the  largest  ;  and  between 
each  pair  of  large  we  have  intermediate  and  small  leaves,  which  extend  a 
limited  distance  only.  They  consist  of  an  inner  framework  of  muscular  fibres, 
clothed  with  mucous  membrane,  and  studded  with  papillae,  some  of  which  are 
small,  others  large  and  bent,  the  latter  retaining  crude  portions  of  food,  for 
further  trituration  and  maceration,  while  fluid  and  finer  pabulum  pass  directly 
through  into  the  fourth  compartment.  The  papillae  at  the  entrance  of  the 
oesophageal  canal  are  large  and  hooked  ;  perhaps  their  use  is  to  retain  the 
alimentary  material  in  the  cavity,  to  which  end  the  latter  is  also  furnished 
with  a  small  valve  at  the  orifice  leading  into  the  abomasum. 

The  fourth,  the  true  digestive  compartment,  or  abomasum,  is  curved  upon 
itself,  elongated  from  before  backwards,  and  continuous  with  the  psalterium 
about  the  right  sac  of  the  rumen.  The  right  side  is  in  the  epigastric  region,  and 
related  with  the  diaphragm,  while  the  left  contacts  the  rumen.  The  greater 
curvature  is  turned  backwards,  receiving  the  insertion  of  the  great  omentum  ; 
the  lesser  is  directed  upwards,  and  is  attached  by  serous  membrane  to  the 
greater  curvature  of  the  psalterium.  The  base  is  in  contact  with  the  cul-de-sac 
of  the  second,  and  separated  from  the  third  compartment  by  a  constriction. 
The  point,  directed  upwards  and  backwards,  is  continuous  with  the  duodenum, 
forming  the  pylorus,  which  is  constricted  by  a  muscular  ring.  The  interior 
resembles  the  villous  portion  of  the  stomach  of  the  horse,  and  the  mucous 
membrane  is  thrown  into  oblique  folds,  crossing  from  end  to  end  in  a  spiral 
direction.     The  serous  coat  is   a  continuation   of  the   great  omentum,  the 


EUMINANTIA— DIGESTIVE   SrSTEM.  371 

muscular  resembles  that  of  the  horse,  while  the  mucous  is  covered  by  a  thin 
layer  of  epithelium,  and  studded  with  glands  and  follicles,  which  secrete 
gastric  juice. 

The  stomach  thus  described  may  be  termed  the  typical  ruminant  stomach, 
as  it  exists  in  the  cavicornia,  and  in  most  deer  (constituting  the  group 
Cotylophora  of  Professor  Huxley).  In  the  camel  there  are  certain  compart- 
ments or  diverticula  in  the  rumen,  which  serve  to  store  up  a  quantity  of  water. 
The  psalterium  is  devoid  of  leaves,  and  is  not  well  developed.  In  one  group 
of  deer,  Tragulus,  the  psalterium  may  be  said  to  be  absent,  being  represented 
only  by  a  short  tube  joining  the  reticulum  and  abomasum  ;  in  this  group  the 
oesophagus  marks  the  line  of  separation  between  the  rumen  and  the  reticulum. 

By  most  of  the  best  authorities  the  process  of  rumination  is  believed 
to  be  effected  somewhat  as  follows  : — The  food  having  been  masticated  and 
swallowed,  falls  icto  the  first  compartment,  where  it  is  tossed  about  by 


Fig.  132. 
Stomach  of  a  Miisk  Deer,  left  aspect— the  last  three 
compartments  opened  and  reflected  forwards.  Rn, 
Kumen  ;  Rt,  Eeticulum  ;  Ah,  Abomasum  ;  Py,  Pylorus  ; 
OS,  CEsophagus ;  X,  Opening  of  the  tube  which  represents 
the  psalterium  ;  Spl,  Spleen. 

muscular  action  and  saturated  with  fluid  ;  a  portion  is  thrown  up  through  the 
valvular\  opening  into  the  reticulum,  and  gains  a  further  supply  of  mucous 
fluid,  and  the  finer  are  separated  from  the  coarser  pai-ticles  ;  the  former  pro- 
ceed to  the  psalterium  ;  the  latter,  by  the  muscular  contraction  of  the  reticu- 
lum, the  relaxation  of  the  cesopbageal  pillars,  and  anti-peristaltic  action  of  the 
oesophageal  walls,  is  returned  to  the  mouth  to  be  remasticated,  and  once  more 
swallowed  ;  a  portion  now  passes  into  the  rumen,  the  remainder  down  the 
oesophageal  canal  to  the  psalterium,  whence  liquids  flow  onwards  to  the 
abomasum,  while  solids  are  drawn  between  the  leaves  of  the  psalterium  to  be 
further  prepared. 

The  Intestines. 

The  small  intestine  of  the  ox  differs  little  from  that  of  the  horse,  except  that 
it  is  smaller  in  calibre,  but  on  an  average  double  the  length.  Beyer's  patches 
are  larger,  but  not  so  numerous. 


372 


COMPARATIVE    SPLANCHNOLOGY. 


Fig.  133. 
Mesentery  and  intestines  of  an  Ox.— 1 1,  Duodenum.    2  2  2,  Small  intestines.    3,  Caecxun. 
4  4,  Colon.    .6,  Rectum.    6  6,  Great  mesentery. 


Fig.  134. 
Caecum  and  origin  of  colon  of  an  Ox— inflated,    a,  Terminal  portion  of  the  ileum 
6,  Caecum  ;  c,  Origin  of  colon. 


RUMINANTIA DIGESTIVE    SYSTEM. 


373 


The  c<Bcum  is  devoid  of  longitudinal  bands,  and  terminally  of  transverse 
furows.  Its  blind  extremity  is  blunt,  rounded,  and  directed  backwards,  and  it 
floats  free  in  the  abdomen.  The  other  extremity,  having  received  the  insertion 
of  the  ileum,  is  continuous  with  the  colon,  which  likewise  wants  bands  and 
furrows.  The  colon  soor-  becomes  greatly  constricted  ;  then,  preserving  about 
the  same  diameter  throughout,  it  is  arranged  in  an  irregularly  elliptic  coil 
between  the  folds  of  the  mesentery. 

Thus  there  is  no  distinct  separation  between  the  great  and  floating  colon  as  in 
the  horse.  The  total  length  of  the  large  intestine  in  the  ox,  from  the  caecum  to 
the  rectum,  is  cbout  36  feet,  but  its  capacity  is  much  less  than  it  is  in.  the 
horse.  Apart  from  the  question  of  measurement,  these  remarks  will  apply  to 
ruminants  generally. 

Accessory  Organs  of  Digestion, 
The  liver  of  the  ox,  situated  in  the  right  hypochondriac  region  is  very  thick. 


Fio.  135. 

Posterior  view  of  the  liver  of  an  Ox.    a,  Left  lobe  ;  h,  Eight  lobe  ;  c,  Spigelian  lobe  : 

d,  Quadrate  lobe  ;  e,  Superior  border  ;  <f,  Anterior  fissure  ;  /,  Inferior  border ;  /,  Notch 

for  the  umbilical  vein  ;  g,  Gall  bladder ;  hhh,  Biliary  tubes  ;  i,  Cystic  duct ;  k,  Ductus 

choledochns. 


and  has  two  large  lobes,  right  and  left,  with  a  Spigelian  lobe,  and  a  small  quad- 
rate lobe  situated  supero-posteriorly.  It  is  provided  with  a  pear-shaped  gall 
bladder  attached  above,  and  lying  upon  its  posterior  surface.  The  gaU  bladder 
ia  furnished  with  three  coats,  serous,  muscular,  and  mucous,  and  it  is  con- 
tinuous with  the  biliary  ducts.  The  cystic  duct  extends  from  the  gall  bladder 
almost  to  the  transverse  fissure,  where  it  joins  the  ductus  choledochus  ;  in  the 
ox  the  latter  enters  the  duodenum  singly,  in  advance  of  the  pancreatic  duct, 
being  guarded  at  its  orifice  by  a  valve-like  doubling  of  the  mucous  membrane. 


374  COMPAKATIVE   SPLANCHNOLOGY. 

In  the  smaller  ruminants  there  is  formed  a  ductus  communis.     The  camel  haa 
no  gall  bladder. 

The  pancreas  presents  no  comparative  feature  of  interest,  excepting  that  its 
duct  forms  in  the  ox  no  ductus  communis,  but  enters  the  duodenum  separately. 
The  spleen  is  of  one  thickness  throughout,  with  two  rounded  extremities  ;  it 
adheres  to  the  left  side  of  the  rumen  and  the  diaphragm,  but  is  not  supported 
by  the  great  omentum. 

EESPIRATORY    SYSTEM. 

The  nostrils  are  narrow,  and  are  capable  of  little  dilatation  compared  with 
those  of  the  horse.  The  nasal  fossae  differ  chiefly  in  there  being  an  additional 
third  turbinal,  the  olfactory  fossa,  and  in  the  arrangement  of  the  frontal  sinuses, 
which  extend  over  the  cranium,  and  are  continuous  with  the  cavities  in  the  horn 
cores  (see  p.  100).  The  nasal  chambers  communicate  at  the  posterior  nares 
below  the  inferior  border  of  the  vomsr,  and  eacli.  of  them  contains  a  structure 
called  the  ca7ial  of  Jacobson,  communicating  with  the  mouth.  It  commences 
in  the  floor  of  the  nasal  chamber,  at  the  base  of  the  septum,  on  each  side  of  the 
vomer,  proceeds  forwards,  and  terminates  behind  the  pad  in  front  of  the  palate. 
It  contains  a  number  of  mucous  foDicles  ;  its  use  is  unknown.  The  larynx  is 
simpler  in  structure,  the  lateral  ventricles  and  true  vocal  cords  being  only 
slightly  developed.  The  trachea  presents  no  important  variation.  We  may 
note  the  presence  of  a  third  bronchus,  which  passes  to  the  right  lung  to  supply 
a  lobe  which  is  wanting  in  the  horse. 

The  thoracic  cavity  is  relatively  smaller  in  the  nmiinant,  and  the  pleurae 
present  a  very  important  deviation  from  the  arrangement  found  in  the  solipede 
— viz.,  the  posterior  mediastinum  is  imperforate  and  strong,  completely  separ- 
ating one  pleural  sac  from  the  other.  This  arrangement  exists  in  all  the 
domesticated  mammals  but  the  solipede. 

The  left  lung  is  divided  into  two  lobes,  the  right  into  four,  the  anterior  one 
recurving  over  and  almost  covering  the  front  of  the  heart.  The  interlobular 
cellular  tissue  is  exceedingly  thick,  the  separation  between  the  lobules  being 
distinctly  visible.  This  arrangement  explains  perfectly  the  special  nature  of 
pneumonic  lesions  in  the  larger  ruminants. 

URINARY   SYSTEM. 

In  the  comparative  anatomy  of  the  kidney,  the  chief  variation  from  the 
simple  type  consists  in  the  gland  being  more  or  less  divided  or  lobulated. 
In  some  animals  the  kidney  is  so  lobulated  as  almost  to  resemble  a  bunch 
of  grapes,  each  lobule  having  its  own  blood-vessels  and  excretory  duct.  This 
subdivision  is  constant  in  all  animals  in  early  foetal  life  ;  but  in  the  majority, 
the  parietes  of  the  lobules  coalesce,  and  the  organ  becomes  a  single  mass.  The 
kidney  of  the  ox "  is  intermediate  in  form,  the  medullary  or  inner  substance 
of  the  organ  being  united,  while  the  cortical  or  outer  substance  is  divided 
into  lobes.  The  pelvis  consists  of  a  principal  cavity,  with  a  diverticulum  or 
calyx  for  each  lobule,  the  uriniferous  tubes  of  each  calyx  opening  on  a  papilla. 
The  general  form  of  the  gland  is  ovoid  and  elongated  ;  in  the  smaller  rami- 


RUMINANTIA GENITAL    SYSTEM.  375 

nants  tlie  kidney  is  simple  in  form,  resembling  in  a  general  sense  tliat  of  tb* 
torse. 


Fia.  136. 
Lobulated  Kidney  of  an  Ox. 

The  Hadder  calls  for  little  remark  ;  it  is  larger,  and  its  peritoneal  coveriag 
extends  further  backwards  than  in  the  horse. 

GENITAL    SYSTEM. 
Male  Organs. 

The  testicle  is  ovoid  and  well  developed,  its  long  axis  being  nearly  vertical ; 
the  mediastinum  is  very  strong.  The  epididymis  presents  a  well-marked 
globus  major ;  the  globus  minor  gives  off  inferiorly  a  free  projection,  which 
doubles  upon  itself  and  leads  to  the  vas  deferens  ;  the  bulbous  portion  of  the 
latter  joins  its  fellow  at  the  neck  of  the  bladder,  forming  the  common  deferent 
canal,  which  opens  by  two  orifices,  into  the  urethra.  The  vesiculce  seminales 
are  large,  lobulated,  yeUow  in  colour,  and  essentially  glandular  in  structure  ; 
they  have  been  termed  the  lateral  prostates,  and  they  discharge  into  the  com- 
mon deferent  canal.  The  urethra  gradually  diminishes  in  calibre  from  its 
origin  ;  its  most  prominent  feature  is  that  just  before  the  pubis  it  describes 
a  double  curve  on  itself,  something  like  a  letter  S.  The  prostate  gland  is 
small,  but  it  extends  posteriorly  under  Wilson's  muscle  ;  Cowper's  glands  are 
wanting,  according  to  some  authorities,  while  others,  Leyh  among  the  number, 
describe  them  as  being  present,  though  small. 

The  penis  of  the  ruminant  is  long  and  thin,  and  projects  far  under  the 
abdomen.  Like  the  urethra,  it  is  bent  upon  itself,  in  the  form  of  the  letter 
S,  a  little  anterior  to  the  bulb,  the  inferior  curvature  being  forwards,  the 
superior  backwards.  About  the  level  of  these,  the  suspensory  ligaments  join 
the  penis,  and  extend  to  its  extremity.  The  glans  is  small  and  attenuated, 
the  canal  of  the  urethra  ending  in  front  in  a  narrow  whip-like  process  of  the 
corpus  spongiosum,  which  is  covered  by  a  rosy,  papillated,  and  sensitive 
integument.  The  sheath  extends  much  farther  forwards  than  in  the  horse, 
and  presents  at  its  opening  a  number  of  long  stiff  hairs,  the  prepuce  being 
prolonged  as  an  elastic  sheath.  It  is  furnished  with  four  thin  muscles — two 
anterior  and  two  posterior.  The  anterior  are  protractors,  restoring  the  prepuce 
to  its  normal  position  ;  the  posterior,  or  retractors,  draw  the  sheath  backwards 
during  the  erection  of  the  penis.  During  the  erection,  the  curves  in  the  penis 
are  effaced,  but  when  quiescent,  and  drawn  into  the  sheath  by  the  retractor 
muscles,  the  curvatures  are  re-formed. 

The  urethra  is  completely  enveloped  by  the  fibrous  sheath  of  the  corpus 
cavemosum  ;  the  latter  is  little  developed. 


576 


COMPARATIVE    SPLANCHNOLOGY. 


Female  Organs. 

In  the  female  ruminant  the  ovaries  are  comparatively  small.  The  ntervs 
presents  generally  the  typical  arrangement ;  its  cornua  are  slightly  twisted, 
and  the  ligaments  are  large  ;  the  fundus  is  short  and  narrow. 

The  mucous  membrane  of  the  uterus  presents  a  number  of  rounded  vascular 
processes,  which  exhibit  eminences  and  depressions ;  these  are  termed  the 
maternal  cotyledons,  and  their  function  is  a  foetal  one.  During  gestation  the 
lateral  walls  of  the  vagina  are  transversed  by  a  mucous  canal,  which  opens 
into  the  vulva  on  either  side  of  the  meatus  urinarius  ;  these  are  the  canals 
of  Gartner,  but  their  use  is  unknown  ;  they  are  not  found  in  the  smaller 
ruminants. 

The  labia  of  the  vulva  are  thick  ;  its  inferior  commissure  is  narrow  and  fur- 
nished with  a  few  hairs.      Inside   the  vulval  cavity  we  have  to  note  the 


Fic.  137. 

Longitudinal  vertical  section  through  the  vagina  and  bladder  of  a  cow. 
a,  Vagina  ;  6,  Vulva ;  c.  Openings  of  Gartner's  canals  ;  d,  Bladder ;  e,  Urethra ; 
/,  Urethral  diverticulum  ;  g,  Clitoris  and  fossa  navicularis ;  h  W  k,  Constrictors  ; 
i  i,  Constrictor  vaginae. 


peculiar  vulvo-vaginal  glands ;  also  a  small  blind  cavity  or  diverticulum  in. 
the  wall  of  the  urethra,  covered,  by  a  fold  of  mucous  membrane. 

The  mammary  glands  constitute  an  organ  termed  the  udder,  which  is  com- 
posed of  two  symmetrical  halves,  placed  one  against  the  other.  Each  half  is 
again  divided  into  two  distinct  glands,  each  with  its  own  teat,  so  that  the 
udder  consists  of  four  mammae  and  four  teats  ;  behind  this  there  may  be 
two  small  rudimentary  teats.  In  the  centre  of  each  quarter,  just  at  the  base 
of  the  teat,  is  a  large  galactopherous  sinus,  the  general  receptacle  of  all  the 
lactiferous  conduits.  From  this  sinus,  which  is  sometimes  large  enough 
to  contain  a  quart,  proceeds  down  the  centre  of  the  teat  one  definite  excretory 
canal. 

In  the  small  ruminants  there  are  two  mammae  and  two  teats,  constructed 
like  those  of  the  cow. 


OMNIVORA. DIGESTIVE   SYSTEM. 


377 


.  Fig.  138. 
Skull  of  a  Hog— showing  the  teeth. 


OMNIYORA. 
DIGESTIVE   SYSTEM. 

In  the  hog  the  mouth  is  large,  the  labial  fissures  extending  far  backwards ;  the 
Tipper  lip  is  confounded  with 
the  snout,  while  the  under  one 
is  short  and  pointed.  The 
canal  of  Jacobson  opens  to- 
wards the  front  of  the  hard 
palate  by  a  small  orifice.  The 
tongue  and  velum  palati  ai-e 
like  those  of  the  smaller 
ruminants,  but  the  filiform 
papUlse  of  the  former  are 
more  developed. 

The  parotid  and  submaxil- 
lary  glands  have  relative  pro- 
portions similar  to  those  of 
the  ruminant.  There  are  two 
sublingual  glands  on  either 
side ;  one  long  and  straight, 
situated  near  the  angle  of  the 
jaw,  and  terminating  in  a 
single  duct,  which  opens  near 
that  of  the  submaxillary  ;  the 
■other,  flat  and  four-sided,  is 
the  true  sublingual,  end  lies 
in  front  of  the  former,  open- 
ing along  the  lower  dental 
arch  by  eight  or  ten  ducts. 

The  hog  is  one  of  the  few 
existing  animals  which  pos- 
sesses what   Professor  Owen 
regards  as  the  typical  mammalian  number  of  teeths  its  permanent  dental 
formula  is  this  : — 


stomach  of  a  Hog— inflated,  o.  Cardiac  portion ;  b.  Its 
accessory  cul-de-sac;  c.  Pyloric  portion  ;  d,  Lesser  curva- 
ture ;  e,  Greater  curvature;  /,  CEsophagQs;  g,  Pylorio 
orifice. 


3-3 
3-3' 


1-1 
1-1' 


p.m. 


4-4 


44. 


Uhe  incisors  differ  from  each  other  in  a  remarkable  degree  ;  the  central  and 
lateral  ones  in  the  upper  jaw  resemble  the  corresponding  ones  in  the  horse, 
having  cavities  in  their  tables,  while  the  upper  corner  incisors  are  isolated,  and 
email  in  proportion  to  the  other  four.  The  central  and  lateral  incisors  of  the 
lower  jaw  are  long,  nearly  straight,  projecting  forwards,  and  somewhat  resem- 
bling the  incisors  of  the  rodent;  the  lower  corner" incisors  are  also  iaolated, 
but  smaller  than  those  of  the  upper  jaw.    The  canine  teeth  are  well  developed. 


378  COMPARATIVE    SPLANCHNOLOGY. 

especially  in  the  male,  having  the  character  of  tusks  ;  the  lower  ones  are  the 
largest,  and  curve  outwards  aiid  upwards  ;  the  upper  pass  outwards  and  down- 
wards.    The  tusks  continue  to  grow  during  the  life  of  the  animaL 

The  molars  also  vary  in  shape,  gradually  increasing  from  the  first  to  the  last,, 
which  is  large  and  strong ;  they  are  intermediate  between  herbivorous  and 
carnivorous,  and  somewhat  resemble  the  human  teeth.  The  first,  which  ia 
small,  and  corresponds  to  the  v/olf-tooth  of  the  horse,  is  a  permanent  or  trae 
molar,  the  next  three  are  the  premolars,  and  the  remaining  three,  true  molars. 

The  stomach  is  simple  and  somewhat  capacious ;  it  consists,  as  in  the  horse,  of 
two  divisions,  cardiac  and  pyloric,  the  latter  being  the  smaller,  but  the  division 
externally  is  marked  by  a  much  more  distinct  constriction.  At  the  upper  and 
left  portion  of  the  cardiac  half  is  a  small  diverticulum  or  cul-de-sac.  The 
oesophagus  is  infundibuliform  at  its  termination.     The  mucous  membrane,  for 


Cfficum  and  colon  of  a  Hog— inflated. 
d,  Kectum. 

the  most  part  villous  in  its  structure,  forms  two  folds  which  extend  from  the 
cardiac   towards   the   pyloric  orifice,   representing   undeveloped   oesophageal 
pillars  and  canal. 

In  the  general  sense  the  intestines  resemble  those  of  the  ruminant,  but  only 
the  posterior  part  of  the  colon  lies  between  the  folds  of  the  mesentery.  A 
Peyer's  patch  of  enormous  size  occurs  at  the  terminal  portion  of  the  small 
intestine.  The  ccecum  resembles  that  of  the  horse  in  having  longitudinal 
muscular  bands,  three  in  number,  and  transverse  constrictions,  and  that  of  the 
ruminant  in  its  shape,  and  the  direct  continuity  of  its  canal  with  that  of  the 
colon ;  the  latter  is  coiled  in  a  similar  manner  to  that  of  the  ruminant. 


OMNIVORA — URINO-GENITAL    SYSTEM.  379 

The  liver  of  the  hog  consists  of  four  chief  lobes  ;  a  right  and  left  external, 
and  a  right  and  left  internal ;  a  small  quadrate  and  a  Spigelian  lobe  exist,  the 


Fig.  141. 
Liver  of  a  Hog— posterior  view,    o,  Right  external  lobe ;  6,  Eight 
internal  lobe ;  c,  Left  external  lobe  ;  d,  Left  internal  lobe ;  e,  Spigelian 
lobe  ;  /,  Posterior  cava  ;  ?,  Quadrate  lobe  ;  h.  Gall  bladder  ;  i.  Cystic 
duct :  k,  Ductus  Cholcdocus. 

latter  being  cleft  by  a  fissure  for  the  posterior  vena  cava.     There  is  a  gall 
bladder,  and  the  biliary  and  pancreatic  ducts  enter  the  intestine  singly. 

RESPIRATORY    SYSTEM. 

The  anterior  extremity  of  the  nose  is  the  snout,  which  is  flat  anteriorly,  and 
presents  on  either  side  the  small,  round  nasal  opening.  Like  the  muzzle  of  the 
ruminant;  it  is  always  damp  in  health.  At  the  anterior,  extremity  of  the  septum 
nasi  is  the  small  snout  bone,  os  rostri,  covered  by  cartilJage  which  extends 
round  the  nasal  openings. 

The  nasal  fossae  are  long  and  narrow.  The  frontal  sinuses  extend  back- 
wards to  the  parietal  bone.  The  larynx  is  loose  and  mobile,  being  attached  to 
the  hyhoid  heel  processes  by  the  epiglottis  rather  than  by  the  thyroid  cai-ti- 
lage.  The  epiglottis  is  very  large  ;  the  lateral  ventricles  are  large  but  shallow. 
The  trachea  and  lungs  resemble 
those  of  the  ruminant,  and,  as 
in  that  animal,  there  is  a  third 
bronchus  ;  the  pleural  sacs 
are  separated  completely. 


Urino-genital  System. 

The  Icidnexj  is  large,  simple  "e 

in  form,  and  like  that  of  the  Fio.  142. 

horse  externally.     The  urini-  Horizontal  section  of  the  kidney  of  a  Hog.    o,  Cortical 

ferous     tubes     discharge     by  ^^8ta°<=e;  h.  Medullary  substance;  c,  B^nal  papillae;  d, 

mi  Infundibulum ;  c.  Ureter  cnt  across, 
papillae    and    cahces.      The 

ureters  enter  the  bladder  very  near  together  ;  the  bladder  itself  is  large,  pro- 
jecting considerably  into  the  abdomen. 


S80  COMPARATIVE    SPLANCHNOLOGY. 

The  testicle  is  large  and  spherical,  being  situated  in  the  perineal  region,  and 
closely  covered  by  the  scrotum.  The  bulbous  portion  of  the  vas  deferens  is 
less  marked,  but  the  vesiculce  seminales  are  large  and  very  glandular  in 
structure,  like  those  of  the  ruminant,  and  diverticular  internally.  There  are 
two  prostate  glands,  an  anterior  and  posterior.  The  latter  may  be  alluded  to 
by  Leyh,  when  he  describes  Cowper's  glands  as  being  very  large  in  this 
animal. 

The  penis  also  resembles  that  of  the  ruminant ;  it  is  long,  thin,  and  pro- 
vided with  a  preputial  sac,  which  secretes  a  peculiar  fluid.  The  sheath  has  no 
muscles. 

In  the  female  the  ovary  is  irregularly  lobulated,  owing  to  the  Graafian 
vesiclep  being  prominent.  The  body  of  the  uterus  is  short,  but  the  cornua 
are  extremely  long,  depending  amoug  the  intestinal  convolutions.  In  the 
vulva  we  find  the  canals  of  Garmer  as  in  the  ruminant,  which  apparently 
originate  in  the  parovarium. 

The  mamma!  usually  number  five  or  six  on  each  side,  arranged  in  a  longi- 
tudinal row  ;  each  gland  has  its  own  teat,  which  is  pierced  by  several  lactifer- 
ous canals,  but  there  are  no  sinuses. 

CARNIVOEA. 
DIGESTIVE    SYSTEM. 

The  lips  of  carnivora  are  thin  and  mobUe,  but  are  not  organs  of  prehension  ; 
the  upper  one  is  mesially  fissured,  and  projects  more  or  less  over  the  lower  ; 
the  latter  is  deutated  posteriorly.  The  upper  lip  of  the  felidge  is  provided 
Avith  long,  straight,  stiff  hairs.  The  hard  palate  is  like  that  of  the  small 
ruminant ;  the  soft  palate  is  very  short ;  the  tonsils  are  well  marked.  The 
buccal  membrane  often  contains  much  pigmentary  matter,  giving  rise  to  large 
patches  of  a  black  colour.  The  tongue  is  thin  and  very  mobile.  In  cats,  the 
papillae  on  the  anterior  part  are  numerous  and  horny,  their  points  being 
directed  backwards,  giving  the  organ  a  rough  surface  ;  in  dogs  the  papillae  are 
neither  prominent  nor  hard.  The  parotid  gland  is  small,  its  duct  crossing  the 
masseter  externally.  The  suhmaxillary  gland  is  larger  than  the  parotid,  and 
has  a  small  accessory  gland  anteriorly.  The  sublingual  gland  is  very  small  in 
the  cat,  and  wanting  in  the  dog  ;  in  the  latter  is  the  orbital  gland,  which  is 
placed  under  the  zygoma,  and  in  the  inferior  part  of  the  orbit ;  its  canals  unite 
to  form  the  duct  of  Niickius,  which  opens  into  the  mouth  about  the  last  molar 
tooth. 

The  dog  has  forty-two  teeth,  formulated  thus  : — 

.  3-3        1-1  4-4        2-2      ,„ 

I. ,  c.   ,  p.m.  ,  m.  =  42. 

3-3'        1-1'  ^        4-4'        3-3 

In  the  carnivora  the  crowns  of  all  the  teeth  are  completely  covered  with 
enamel.  The  upper  incisors  are  the  strongest ;  the  corner  ones  are  the  largest, 
the  central  the  smallest.  They,  in  common  with  the  other  teeth,  are  remark- 
able for  their  brilliant  whiteness,  and  present,  when  not  worn  on  their  tables, 
three  tubercles,  a  large  central  and  two  small  lateral  ones,  the  tooth  somewhat 
resembling  a  trefoil  or  fleur-de-lin.     As  the  animal  ages,  these  projections  wear 


CARNIVORA DIGESTIVE    STSTEHL 


381 


away.  The  canines,  temporary  and  permanent,  are  very  large,  strong,  conical, 
and  curved  outwards  and  backwards  ;  the  upper  ones  are  the  largest,  and  have 
a  space  between  them  and  the  incisors,  which 
lodges  the  lower  canines  when  the  mouth  is  shut. 
The  molars,  twelve  in  the  upper,  and  fourteen 
in  the  lower  jaw,  terminate  in  sharp  projections  ; 
the  last  upper  premolar  and  the  first  lower  true 
molar  are  the  largest,  and  being  furnished  with 
cutting  edges,  they  have  been  termed  the  sectorial 
teeth,  dens  sectorius  ("dent  carnassiere"  of 
Cuvier).  The  other  molars  are  slightly  sectorial, 
and  also  tuberculate — i.e.,  provided  with  pro- 
cesses for  crushing  the  food. 

The  cat  has  only  fourteen  molars,  eight  above  and  six  below ;  the  other 
teeth  are  like  those  of  the  dog,  making  up  a  total  of  thirty.  The  formula 
probably  is  : — 

.  3-3  ^    1-1   „^   8-3  ^  l-l_on 

^.  ,  c.      — ,  p.m.  ,  m. =  60. 

3-3         1  - 1'  ^        2-2         1-1 

The  last  upper  premolar,  and  all  the  lower  molar  and  premolar  teeth  may  be 
eaid.  to  be  sectorial  in  this  animal. 

The  oesophagus  is  very  dilatable,  and  presents  a  well-marked  infundibtili- 
form,  union  with  the  stomach. 


Fio.  143. 
Teeth  of  a  Lion  (Camivora). 


Fig.  144.  FiQ.  145. 

of  a  Dog -inflated,    a,  Cardiac  per-  Caeeum  and  colon  of  a  Dog— inflated, 

tion  ;  6,  Pyloric  portion ;  c,  (Esophageal  orifice ;  o.  Ileum ;  b,  Caecum  ;  c,  Colon. 
d.  Duodenum. 

The  stomach  is  simple  and  only  slightly  curved  ;  it  is  commonly  described 
as  pear-shaped,  resembling  that  of  the  horse,  but  with  a  very  small  and  narrow 
pyloric  portion,  terminating  in  a  constricted  valve.  The  mucous  membrane  is 
ail  villous,  the  natural  food  of  these  animals  requiring  but  little  preparation. 

The  intestines  are  short  and  small.  The  small  intestine  is  suspended  by  a 
mesentery ;  its  walls  are  thick.  The  colon  is  somewhat  larger  than  the  small 
intestines,  and  divided,  as  in  man,  into  ascending,  transverse,  and  descending 
portions  ;  the  caecum  is  only  a  smaU,  spiral  appendix  ;  there  is  no  floating 


382  COMPARATIVE  SPLANCHNOLOGY-. 

colon.     Near  the  anus,  the  rectum  presents  on  either  side  the  openings  of  twf> 
glandular  pouches,  where  is  secreted  a  strong  foetid  matter. 

Accessory  Organs  of  Digestion. 

Tlie  liver  is  large,  and  deeply  cleft  into  five  lobes,  a  gall  bladder  being 
lodged  in  the  middle  lobe.  The  biliary  duct  unites  with  a  small  duct  from  the 
pancreas  before  entering  the  duodenum. 

The  pancreas  is  elongated,  running  along  the  concave  curvature  of  tbe  dxio- 
denum ;  its  anterior  end  reaches  the  lesser  curvature  of  the  stomach.  There 
are  two  ducts,  a  large  one  entering  the  duodenum  alone,  and  a  smaller,  wbich. 
joins  the  bile  duct. 

The  spleen  is  long  and  irregularly  club-shaped.  Tt  is  suspended  in  the  great 
om>entum,  near  the  left  sac  of  the  stomach.  Its  thick,  blunt  extremity  is. 
placed  anteriorly. 


Fig.  146. 
Stomach,  Liver,   Pancreas,  and  Duodenum  of  a  Dog.      a  a,  Liver ; 
b,  Gall-bladder ;  c  c,  Biliary  Canals  ;  d.  Cystic  Duct  ;  e,  Ductus  Chole- 
docus  ;  /,  Pancreas  ;  g,  Pancreatic  Ducts. 

RESPIR.^TORY  SYSTEM. 
The  septum  nasi  is  prolonged  on  either  side,  thus  taking  the  place  of  the 
alar  cartilages,  and  being  continuous  with  the  cartilaginous  prolongations  of 
the  inferior  turbinals.  There  is  only  One  maxillary  sinus  on  each  side.  The 
thoracic  cavity  is  usually  very  large  in  carnivora.  The  lungs  are  divided,  the 
left  into  three,  the  right  into  four  lobes,  by  clefts  which  reach  almost  to  the 
root  of  the  organ.  The  heart  is  completely  surrounded  by  the  lungs,  not 
embedded  in  depressions  in  them.  The  pulmonary  tissue  is  very  compact,  the 
lobules  being  small,  while  the  air-cells  are  well  developed. 

URINARY  AND   GENITAL   SYSTEMS, 
The  kidney  is  ovoid,  but  shorter  than  in  the  hog ;  in  the  cat  it  is  still 
shorter,  being  almost  round.     The  pelvis  is  simple,  presenting  a  single  large 
elongated  papilla.     The  bladder  is  furnished  with  a  very  strong  muscular  coat. 


RODENTIA.  383" 

The  testicles  are  situated  in  the  perineal  region,  below  the  anus.  The 
vesicul<e  seminales  are  wanting,  but  the  prostate  is  large,  forming  a  con- 
spicuous bulb  around  the  origin  of  the  urethra.  Cowper's  glands  are  wanting 
in  the  dog,  and  are  small  in  the  cat.  The  penis  of  the  dog  is  long,  and  termi- 
nates in  a  point.  In  common  with  the  camivora  generally,  a  bone  is  found  in 
the  penis  ;  its  anterior  extremity  is  fixed  in  the  glans,  while  the  posterior  is 
attached  to  the  corpus  cavernosum,  occupying  all  that  portion  of  the  organ 
which  is  lodged  in  the  sheath.  The  os  penis  is  long  and  curved,  presenting  an 
inferior  gutter,  in  which  the  urethra  is  placed,  continuous  with  the  groove  of 
the  corpus  cavernosum  ;  it  favours  the  introduction  of  the  penis  into  the  vulva. 
In  the  dog,  the  corpus  spongiosum  forming  the  glans  undergoes  a  very  remark- 
able degree  of  tumefaction,  which  retains  the  two  sexes  in  coitw  for  a  con- 
siderable time.  The  differences  in  the  female  organs  are  unimportant.  In  the 
cat,  the  penal  bone  is  not  so  well  developed,  and  the  penis,  when  relaxed,  is 
turned  backwards  ;  when  erect,  it  assumes  the  same  position  as  in  other  car- 
nivora.  In  the  female,  a  small  bone  exists  in  the  clitoris.  The  mammae  are 
arranged  as  in  the  sow. 

RODENTIA. 

The  front  teeth  form  one  of  the  leading  characteristics  of  the  rabbit.  The 
iental  formula  is — 

. 2-2         0-0  3-3         3-3      „„ 

^•rrr  '•  O^'P-"'-  232' '^•333  =  28. 

The  upper  incisors  consist  of  a  large,  curved,  chisel-shaped  pair,  which  grow 
from  permanent  pulps ;  they  are  covered  with  enamel  only  on  their  anterior 
surface,  which,  wearing  more  slowly 
than  the  rest,  gives  rise  to  the  chisel- 
like edge.  The  second  pair  of  upper 
incisors  are  situated  immediately 
behind  the  first,  and  are  remarkably 
small.  The  lower  incisors  resemble 
in  most  respects  the  large  upper 
ones. 

There  is  an  enormous  diastema.  show  the  arrangement  of  Eodent  Teeth, 


Fio.  147. 
Lateral  half  of  Mandible  of  a  Rabbit,  opened  to 


The  molar  and  premolar  teeth  have 

compound  transversely  ridged  tables,  and  grow  from  permanent  pulps.^ 
The  large  papillae  of  the  tongue  appear  as  two  well-marked  oval  spaces,  the 
papillcB  foliatcB,  one  on  each  side  posteriorly,  not  upon  the  dorsum.    Thes^ 
contain  the  minute  organs  of  taste,  which  occur  in  the  larger  papillte  of  the 
horse's  tongue. 

The  stomach  is  simple  in  structure.  The  cmcum  is  long,  being  slender  and 
glandular  at  its  termination.  The  liver  and  pancreas  are  both  large,  and  the 
pancreatic  duct  enters  the  intestine  far  behind  the  biliary  duct. 

The  testicle  is  large,  ovoid,  sometimes  scrotal,  sometimes  abdominal  in  situa- 
tion ;  in  the  latter  case  it  is  fixed  by  the  gubemuculum  testis.  The  vai 
deferens  is  so  separated  from  the  blood-vessels  that  the  spermatic  cord  is 
really  double.  The  vasa  discharge  into  the  urethra  on  each  side  of  the 
duct  of  a  large  uterus  masculinus,  described  by  some  authorities  as  a  single 
median  vesicula  seminali§. 


384  COMPARATIVE    SPLANCHNOLOGY. 

is  the  possession  of   two  uteri,  each  uterus  opening  into   the  vagina  by  a 
distinct  orifice ;   the  two  are  near    together   posteriorly,  and   anterially  they 
diverge,     Tlie  vulva  has  both  major  and  minor  labia,  and  the  clitoris  is  large 
and  very  prominent. 

"  The  following  principal  forms  of  uterus  are  found  in  the  mammalia  : — 
The  simple  uterus  (uterus  simplex),  in  woman  and  the  monkey  ;  the  two-horned 
uterus  (uterus  bicornis),  in  the  mare  and  ruminant ;  the  bifurcated  uterus 
Cuterus  divisus),  in  the  sow  and  carnivora ;  and  the  double  uterus  (uterus  duplex), 
in  the  rodent." — France.  ' 

AVES, 

For  many  reasons,  this  part  of  the  subject  is  interesting,  but  very  little  space 
can  be  given  here  to  its  discussion. 

Birds  have  no  teeth,  the  maxillse  being  covered  anteriorly,  on  the  outside, 
by  a  homy  modification  of  the  integument,  the  wbole  constituting  the 
rostrum  or  beak  The  tongue  is  horny  in  structure,  and  apparently  an  organ 
of  prehension,  not  of  taste.  The  cesophagus  is  very  long,  and  its  longi- 
tudinal muscvilar  coat,  is  internal,  the  circular  external.  In  seed-eating 
birds,  the  esophagus  expands  in  the  cervical  region  into  the  ingluvies,  or 
crop, — a  large  sac  which  rests  upon  the  fascia  connecting  the  clavicles,  and  in 
which,  maceration  of  the  food  is  carried  on.  The  oesophagus  is  then  con- 
tinued and  expanded  into  the  first  cavity  of  the  stomach,  the  proventrioulus,  a 
very  vascular  and  glandular  cavity,  where  a  fluid  analogous  to  the  gastric 
juice  is  secreted.  To  this  portion  succeeds  the  second  or  muscular  cavity, 
the  gizzard,  which  is  oval  and  flattened  in  shape,  but  with  a  structure  vary- 
ing according  to  the  nature  of  the  animal's  food.  In  granivorous  or  seed- 
eatincf  birds,  the  muscular  coat  possesses  extraordinary  thickness  and  strength, 
wbile  the  lining  membrane  exhibits  a  dense,  horny,  epithelial  structure. 
In  the  upper  portion  are  two  orifices,  a  large  one  opening  into  the  proven- 
triculus,  and  just  to  the  right  of  this  a  smaller  pyloric  orifice  opening  into  the 
duodenum.  All  the  domesticated  birds  possess  a  gizzard  similar  to  this,  but 
in  those  birds  which  feed  naturally  on  flesh,  the  walls  of  the- gizzard  are  mem- 
branous in  their  thinness,  the  development  of  the  organ  being  usually 
correlated  with  the  size  of  the  ingluvies. 

Granivorous  birds  always  s^vallow  a  quantity  of  stones  or  sand,  which  is 
deposited  in  the  gizzard,  and  with  the  action  of  the  muscular  wall  and  horny 
lining,  assists  in  grinding  the  ingesta  to  a  pulp.  Thus  the  gizzard  may  be 
viewed  as  an  organ  of  mastication. 

The  intestines  are  very  much  shorter  than  in  the  mammalia,  the  layers  of 
muscular  fibre  being  inversely  arranged,  as  in  the  oesophagus.  There  are  two 
separate  cwca,  long  and  narrow,  with  their  blind  ends  directed  forwards.  The 
duodenum  forms  a  loop  or  bend  near  its  origin,  embracing  the  pancreas  ;  the 
rest  of  the  small  intestine  is  suspended  by  a  mesentery.  The  large  intestine  is 
very  short,  running  straight  from  the  cseca  to  the  termination  of  the  canal ;  it 
is  commonly  termed  the  rectum,  and  it  opens  into  a  cavity  called  the  cloaca, 
an  excretory  recess,  comwon  to  the  alimentary,  urinary,  and  genital  organs. 

The  pancreas  usually  consists  of  two  distinct  pieces,  and  its  ducts  are  two  in 
number,  opening  separately  into  the  duodenal  loop.  The  liver  is  very  large, 
and  as  the  diaphragm  is  rudimentary,  it  can  hardly  be  regarded  as  a  pure 


AVES. 


385 


abdominal  organ.  It  consists  of  tvro  lobes,  between  wbicli,  anteriorly  is  the 
apex  of  the  heart,  and  posteriorly  a  double  fold  of  peritoneum,  analogous  ta 
the  broad  ligament  of  the  mammal.  There  are  two  hepatic  ducts,  one  pro- 
ceeding direct  to  the  duodenum,  the  other  passing  from  the  right  lobe  to  the 
gall  bladder,  a  cystic  duct  proceeding  from  the  latter  to  the  intestine.  The 
ColumbidBB  or  pigeon  class,  as  also  some  classes  of  the  order  Scansores,  have 
no  gall  bladder.     The  vena  porta,  _ 

in  addition  to  its  fundamental 
radicals,  is  joined  by  branches  from 
the  femoral  and  sacral  veins. 

The  organs  of  respiration  in  birds 
are  interesting.  The  nasal  openings 
are  very  small,  and  placed  on  each 
side  of  the  beak,  or  at  its  base, 
surrounded  by  naked  skin,  a  few 
feathers,  or  even  scales,  which  form 
alae  or  wings ;  the  nasal  cavities 
open  into  the  pharynx  by  two  dis- 
tinct apertures,  which  lie  close  to- 
gether. The  air-passages  consist 
of  a  superior  larynx,  trachea,  inferior 
larynx,  bronchi,  bronchial  tubes, 
and  air-sacs.  The  superior  larynx 
is  situated  just  behind  the  root  of 
the  tongue,  opening  by  a  longitu- 
dinal slit.  It  consists  of  several 
bony  or  cartilaginous  pieces,  varying 
in  number,  joined  by  membranes 
and  moved  by  muscles.  There  is 
no  epiglottis,  the  sides  of  the  rima 
closing  the  orifice  during  the  passage 
of  food.  The  trachea  winds  down 
the  neck  as  a  single  tube,  composed 
of  complete  bony  or  cartilaginous 
rings,  not  overlapping,  as  in  mam- 
malia. They  are  round  or  com- 
pressed, varying  in  diameter.  The 
syrinx,  or  inferior  larynx,  is  the 
organ  of  sound,  and  is  best  devel- 
oped in  song-birds,  varying  in  form 
and  structure  in  different  species. 
At  its  origin  is  a  membranous 
tongue,  composed  of  a  doubling  of  lining  membrane  ;  the  free  portion  is 
directed  upwards,  and  its  vibration  produces  sound. 

Below,  the  tube  divides  into  a  pair  of  bronchi,  which  lead  to  the  lungs. 
They  consist  of  incomplete  segments  of  bone  or  cartilage,  completed  by  mem- 
brane. The  lungs  are  spongy,  bright  red,  long,  flat,  oval,  and  applied  against 
the  sides  of  the  vertebrae  and  ribs,  to  which  they  are  attached  by  cellular 

2c 


FIG.  148. 

Alimentary  canal  of  a  Bird,  a,  Ingluvies  :  b, 
Proventricnlus  :  c.  Pancreas ;  d,  Duodenum ;  e. 
Liver ;  /.  Biliary  cyst  and  duct ;  g,  Pancreatic 
duct ;  h.  Intestine  ;  i.  The  two  cseca  ;  k,  itectum  ; 
I,  Eight  ureter ;  m,  Oviduct  ;  n,  Its  aperture  in 
cloaca  ;  o,  Opening  of  cloaca. 


386 


COMPARATIVE  SPLANCHNOLOGY. 


tissue.  They  present  several  openings  on  their  surfaces,  which  communicate 
with  air-sacs  hollowed  out  in  the  cellular  tissue  of  the  body.  These  sacs  are 
continuous  with  the  interior  of  certain  "bones,  which  thus  receive  a  constant 
supply  of  air  (see  p.  119).  There  are  usually  nine  sacs — viz.,  one  inter- 
claviciolar,  and  the  cervical,  anterior  and 
lateral  thoracic,  and  abdominal,  which  are 
pairs.  By  means  of  these,  air  penetrates 
nearly  every  region  of  the  body. 

The  kidney  is  very  irregular  in  shape,  con- 
sisting of  several  portions  which  occupy  the 
osseous  irregularities  in  the  sublumbar  and 
anterior  pelvic  regions.  The  ureters  open  into 
the  cloaca,  a  diverticulum  of  which  is  regarded 
as  the  analogue  of  the  urinary  bladder  ;  the 
latter  organ  is  distinctly  possessed  by  only 
one  member  of  the  class,  the  ostrich. 

The  testicle  is  abdominal,  occupying  almost 
the  position  of  the  mammalian  kidney,  which 
it  resembles  somewhat  in  shape,  being  ovoid. 
There  is  scarcely  any  epididymis  ;  the  vas 
deferens  is  tortuous,  and  it  terminates  in  the 
cloaca  at  the  side  of  a  papilla,  which  is  the 
organ  of  copulation.  In  the  natatores  this 
papilla  is  very  large,  spirally  elongated,  and 
retractile. 

In  the   bird  there  is  only   one  ovary,  the 

right  one  being  undeveloped.      It  resembles 

a  bunch  of  grapes  in  form,  consisting  of  ova 

in  various  stages  of  development ;  the  more 

advanced  ones  are  large,  and  yellow  in  colour. 

The  representative  of   the  Fallopian  tube  is 

called  the  oviduct,  which  is  large,  flexuous, 

and  very  dilatable,  leading  to  the  cloaca.     It 

is  not  merely  the  duct  of  the  ovary,  since  it 

also  assists  in  forming  the  ovum  ;  while  the 

latter  is  passing  through  it,  the  outer  casL;3g  of 

calcareous  material  known  as  the  shell,  and  the  inner  layer  of  albumen  or 

*' white  of  the  egg"  become  developed.      The  coats  of  the  duct  are  seroua, 

anuscular,  and  mucous,  arranged  in  the  typical  manne?;. 


Fio.  149. 

TJrino-genital  organs,  &c.,  of  a 
male  bird  (fowl).  1,  Heart ;  2,  (Eso- 
phagus cut  across  ;  3,  Aorta ;  4,  Pos- 
terior cava ;  5  5,  Psoe  muscles  ;' 
n  o,  Testicles  ;  6  6,  Vasa  deferentia  ; 
i'b',  their  orifices;  ce.  Suprarenal 
capsules;  drf,  Kidneys;  e«, Ureters; 
e'  €,  Their  openings  into  the  cloaca. 


CHAPTER    V. 
ANGIOLOGY. 

tJNDER  this  heading  we  describe  the  organs  of  circulation,  by  the 
action  of  which  certain  fluids  are  propelled  through  the  body 
It  is  customary  to  divide  this  branch  of  the  subject  into  two 
sections,  considering  respectively  the  Blood- Vascular  and  Lym- 
phatic Systems. 

Blood-Vascular  System. 

This  involves  the  consideration  of  the  Blood,  a  fluid  which 
supplies  nutriment  to  the  tissues,  and  receives  eifete  material 
from  them ;  the  Heart,  a  muscular  organ  which,  by  its  contrac- 
tion, initiates  the  motion  of  the  blood  ;  the  Arteries,  a  series  of 
tubes  which  convey  the  blood  from  the  heart  to  all  parts  of  the 
body ;  the  Veins,  tubes  which  return  that  fluid  to  the  heart ; 
and  the  Capillaries,  minute  tubes  joining  the  smaller  arteries 
and  veins. 

BLOOD. 

Blood  is  a  fluid  tissue,  which  nourishes  all  living  structures, 
being  the  medium  by  which  nutritive  material  is  conveyed  to, 
and  effete  or  waste  material  conveyed  away  from,  the  solid 
tissues.  It  is  an  opaque,  thickish,  clammy  fluid,  with  a  peculiar 
odour,  sickly  saline  taste,  and  alkaline  reaction.  Its  colour 
varies  in  different  parts  of  the  same  animal,  that  in  the  arteries 
being  bright  red  or  scarlet,  while  the  blood  in  the  veins  is  of  a 
dark  purplish  hue. 

When  examined  microscopically,  the  blood  is  found  to  consist 
of  minute  corpuscles,  and  a  clear,  transparent,  yellow  fluid,  the 
liquor  sanguinis,  or  plasma,  in  which  the  corpuscles  float. 
The  corpuscles  are  of  two  kinds,  the  red,  and  the  white  or 
colourless  ;  the  former,  by  far  the  more  numerous,  exist  in  vary- 

387 


388  ANGIOLOGY. 

ing  proportions.  Bed  corpuscles  vary  in  shape,  but  in  all 
mamnials  are  more  or  less  discoid,  the  eamelidae  excepted,  where 
they  are  oval ;  in  birds,  reptiles,  and  fishes,  they  are  oval,  and 
also  nucleated.  Their  average  diameter  in  the  horse,  ox,  or 
sheep  is  about  4^Vo^^  P^^^  of  an  inch,  their  average  thickness 
being  about  one-fourth  of  this.  Each  surface  is  depressed 
towards  its  centre,  hence  the  corpuscle  is  appropriately  described 
as  a  bi- concave  disc.  ^ 

The  white  corpuscles  are  larger  than  the  red,  round  in  shape, 
and  nucleated.  Occurring  also  in  lymph  they  are  sometimed 
termed  h/mph-co7'puscles. 

The  liquor  sanguinis  is  pale  and  clear,  and  consists  of  water, 
fibrin,  albumen,  fatty  compounds,  extracts,  odoriferous  and  salinft 
matters.  The  serum  is  a  thin,  transparent  liquid,  of  a  pale- 
straw  or  yellow  colour,  consisting  of  the  liquor  sanguinis  deprivec) 
of  fibrin.  It  contains  nearly  90  per  cent,  of  water,  is  always 
slightly  alkaline,  and  coagulates  when  heated,  owing  to  the  large 
quantity  of  albumen  it  contains.  Fibrin  is  a  white,  stringy, 
elastic  substance,  which,  when  the  blood  is  in  circulation,  is  ir. 
solution,  and  cannot  be  distinguished  from  the  other  constituents 
of  the  plasma. 

HEART. 

The  heart  is  a  hollow,  ipvoluntary  muscular  organ,  situated 
between  the  layers  of  the  middle  mediastinum,  and  in  the  peri- 
cardial sac,  to  a  reflection  of  which  it  owes  its  external  smooth, 
glistening  aspect.  Its  form  is  that  ■  of  a  blunt  cone,  slightly 
flattened  from  side  to  side,  and  it  presents  a  base  and  an  apex. 
The  former  is  turned  upwC..'ds,  a_i  to\.ards  the  dorsal  vei.ebrie, 
from  which  the  heart  is  suspended  by  the  blood-vessels  that 
spring  from  it ;  the  apex  points  downwards,  backwards,  and  to 
the  left  side,  lying  at  about  the  level  of  the  last  bone  of  the 
sternum  ;  the  organ  extends  from  about  the  third  to  the  sixth 
rib  inclusive.  The  average  weight  of  the  horse's  heart  is  about 
six  pounds  and  a-half,  its  length  from  base  to  apex  about  eight 
inches,  its  antero-posterior  diameter  rather  less,  and  its  lateral 
diameter  less  still. 

The  heart  is  divided  by  a  longitudinal  septum  into  a  right 
and  left,  or  anterior  and  posterior  side.  Each  of  these  is  again 
subdivided  by  a  transverse  septum  intO'  two  compartments,  which 
communicate.  Thus  there  are  four  cardiac  cavities,  the  superior 
ones,  whose  free    extremities  somewhat   resemble   the   ears   of  a 


RIGHT    AURICLE.  389 

dog,  being  called  the  auricles,  the  inferior  the  ventricles.  These 
divisions  are  marked  externally  by  deep  grooves,  in  which  the 
cardiac  blood-vessels  run,  and  which  are  generally  filled  with  fat. 
Two  of  these  grooves  extend  from  the  base  of  the  ventricles  to 
the  apex  of  the  heart,  and  correspond  to  the  internal  septum ; 
they  are  called  the  anterior  and  posterior  longitudinal  furrows. 
Around  the  base  of  the  ventricles  is  a  deep  transverse  auricula- 
ventricular  furrow,  which  marks  the  division  of  the  heart  into 
an  upper  or  auricular,  and  a  lower  or  ventricular  portion. 

The  right  side  of  the  heart  is  sometimes  called  the  venous,  the 
left  the  arterial  side,  named  from  the  kind  of  blood  which  passes 
through  them.  We  will  describe  first  the  cavities  of  the  right 
side,  and  then  those  of  the  left. 


RIGHT    AURICLE. 

The  right  auricle  is  the  larger,  and  forms  the  right  and 
anterior  portion  of  the  base.  It  consists  of  two  portions  ;  the 
sinus  venosus,  or  principal  cavity,  is  somewhat  qnadrangular  ;  its 
walls  are  thin,  and  connected  inferiorly  with  the  right  ventricle ; 
internally,  with  the  left  auricle ;  anteriorly,  they  are  prolonged 
to  form  the  appendix.  The  appendix  auricula},  or  proper 
auricle,  is  a  small  conical  *pouch,  which  projects  forwards  from 
the  sinus ;  its  walls  are  thick,  and  its  edges,  more  particularly 
the  outer  one,  serrated.  On  laying  open  the  interior  of  the 
auricle  (which  is  best  done  by  an  incision  from  the  appendix  to 
the  mouth  of  the  posterior  vena  cava,  then  opening  the  anterior 
cava,  and  connecting  the  incisions),  the  smooth  transparent 
Endocardium  or  lining  membrane,  anterior  and  posterior  Yense 
cavse.  Coronary  sinus,  Foramina  Thebesii,  and  right  Auriculo- 
ventricular  opening  are  displayed. 

The  anterior  vena  cava  returns  the  blood  from  the  anterior 
part  of  the  body,  and  opens  into  the  supero-posterior  part  of  the 
sinus  venosus.  The  posterior  cava,  which  returns  the  blood 
from  the  posterior  region  of  the  body,  opens  into  the  infero- 
posterior  part  of  the  external  wall  of  the  sinus,  near  the  inter- 
auricular,  or  superior  part  of  the  longitudinal  septum.  The 
coronary  sinus,  the  dilated  termination  of  the  larger  coronary  or 
cardiac  veins.,  is  situated  below  the  opening  of  the  posterior  cava, 
between  it  and  auriculo-ventricular  opening  ;  and  through  it  the 
blood  is  returned  from  the  substance  of  the  heart.      The  coronary 


390 


ANGIOLOGT. 


valve  or  valve  of  Thehesius,  is  a  fold  of  the  endocardium  which 
covers  the  coronary  sinus,  preventing  regurgitation  of  blood 
during  the  contraction  of  the  auricle.  The  foramina  Thebesii 
are  minute  openings  on  the  inner  surface  of  the  auricle ;  some  of 
them  are  mere  depressions,  whilst  others  are  the  openings  of 
minute  veins,  vence  cordis  minvmce,  which  return  blood  directly 
from  the  substance  of  the  walls.  The  right  auriculo-ventricular 
opening  is  a  large  oval  aperture,  occupying  the  floor  of  the 
auricle ;  it  communicates  with  the  right  ventricle.  The  tuher- 
culum  Lowerii  is  a  slight  projection-  situated  between  the 
openings  of  the  cavse,  and  is  supposed  to  direct  the  blood  from 

the  anterior  cava  into  the 
auriculo-ventricular  open- 
ing. 

In  man  the  remains  of  a 
fcetal  structure,  called  the 
Eustachian  valve  are  situ- 
ated at  the  anterior  margin 
of  the  posterior  cava,  stretch- 
ing from  it  to  the  left  side 
of  the  annulus  ovalis.  It 
is  a  doubling  of  the  lining 
membrane,  largest  in  the 
foetus,  and  serves  to  direct 
the  blood  from  the  vein  to 
the  foramen  ovale;  in  quad- 
rupeds, this  structure,  if 
present  at  all,  is  extremely 
rudimentary. 

The  fossa  ovalis  is  an 
oval  depression  in  the  interauricular  septum,  being  an  obliter- 
ated foramen,  which  in  the  foetus  joins  the  right  and  left 
auricles.  At  birth  this  opening  is  closed.  Its  lower  border 
is  indistinct  ;  its  upper  thick  and  projecting,  forming  the 
annulus  ovalis  or  isthmus  Vieusseni.  The  muscidi  pecti- 
nati  are  columns  of  muscular  fibres  situated  chiefly  in  the 
appendix ;  they  are  called  pectinati,  from  their  resemblance  in 
arrangement  to  the  teeth  of  a  comb.  Smaller  bundles  cross 
the  large  ones,  giving  the  whole  a  reticulated  appearance, 
between  which  are  depressions,  some  of  which  are  the  foramina 
Thebesii. 


Fia.  150. 
Right  side  of  the  heart— laid  open.  1,  Eight  ven- 
tricle ;  a  a,  Its  external  wall ;  6  b,  Carneas  columnse  ; 
c.  Great  moderator  band  ;  d,  Origin  of  pulmonary 
artery  ;  e  e  e.  Sigmoid  valves  ;  2,  Eight  auricle  ;  a  a, 
Foramina  Thebesii  and  musculi  pectinati ;  6,  Opening 
of  anterior,  and  c,  of  posterior  vena  cava. 


RIGHT    VENTEICLE.  391 


EIGHT    VENTRICLE. 


The  blood  leaves  the  right  auricle  through  the  auriculo-ven- 
tricular  opening,  and  enters  the  right  ventricle,  which  occupies 
the  antero-inferior  part  of  the  right  side  of  the  heart.  It  is  some- 
what conical  in  shape,  with  its  base  uppermost,  and  extends  from 
the  auriculo-ventricular  septum  to  near  the  apex.  Its  outer  walls, 
although  thicker  than  those  of  the  auricle,  are  much  thinner  than 
those  of  the  left  ventricle.  The  inner  wall  is  convex,  and  formed 
by  the  interventricular  septum ;  on  laying  the  cavity  open  (by 
an  incision  along  the  side  of  the  anterior  longitudinal  furrow,  and 
a  second  one  below  and  parallel  to  the  transverse  septum,  joining 
the  first),  two  openings  present  themselves. 

The  auriculo-ventricular  is  the  large  oval  opening,  situated  at 
the  base  of  the  ventricle,  surrounded  by  the  fibrous  auriculo-ven- 
tricular ring;  it  communicates  with  the  auricle,  and  is  guarded 
by  the  tricuspid  valve,  which  is  formed  by  a  redoublicature  of 
the  endocardium,  strengthened  by  an  intermediate  layer  of  fibrous 
tissue.  It  consists  of  three  triangular  cusps  or  segments,  which, 
connected  at  their  bases,  surround  the  auricular  opening.  The 
cusps  are  attached  to  each  other  above  for  a  short  distance,  but 
their  apices  freely  project  into  the  cavity  of  the  ventricle  ;  the 
largest  is  placed  between  the  auriculo-ventricular  opening  and  the 
opening  of  the  pulmonary  artery ;  a  second  rests  against  the 
septum  of  the  ventricles,  the  third  between  the  other  two.  The 
free  edges  of  the  cusps  are  thickened,  and  to  their  ventricular 
surfaces  and  free  margins  are  attached  a  number  of  delicate 
tendinous  cords,  or  chordce  tendinece,  which  spring  from  the  inner 
surface  of  the  ventricle.  The  majority  of  these  arise  from  the 
free  blunt  extremities  of  the  muscuU  papillares,  which  are  a 
variety  of  carnece  columnce,  the  remainder  from  the  walls  of  the 
ventricle,  diverging  towards  the  valve  ;  some  terminate  in  the 
free  margins  and  apices  of  the  cusps,  others  in  the  central  thick 
portion  ;  while  a  few  reach  the  attached  borders,  and  become 
continuous  with  the  auriculo-ventricular  ring.  This  valve  pre- 
vents the  regurgitation  of  blood  into  the  auricle  when  the  ventricle 
contracts. 

The  second  opening  in  the  right  ventricle  is  the  origin  of  the 
pulmonary  artery.  It  is  situated  above  and  to  the  left  of  the 
auriculo-ventricular  opening,  is  circular,  and  arises  from  the 
summit  of  a  conical  prolongation  called  the  conus  arteriosus,  or 


392  ANGIOLOGT. 

infundibulum,  whose  smooth  inner  surface  is  destitute  of  carneae- 
columnae.  The  entrance  of  the  pulmonary  artery  is  guarded  by 
three  semilunar  or  sigmoid  valves,  which  consist  of  semicircular 
folds  of  the  lining  membrane  ;  they  are  almost  transparent,  and 
attached  by  their  convex  margins  to  the  tendinous  ring  which 
surrounds  the  origin  of  the  artery.  Their  free  edges  are  almost 
straight,  and  thinner  than  the  attached  ones,  each  presenting  a 
mesian  fibro-cartilaginous  nodule,  the  corpus  Arantii. 

When  blood  passes  from  the  ventricle  to  the  pulmonary  artery, 
tlie  valves  are  laid  against  the  sides  of  the  vessel;  when  the 
current  is  checked,  a  portion  of  it  falls  back  towards  the  ventricle, 
and  the  valves  are  now  thrown  inwards  ;  they  become  distended, 
overlap,  and  completely  close  the  tube.  Wben  the  valves  are 
shut,  the  surfaces  next  the  vessel  are  concave,  the  ventricular  ones 
convex. 

The  corpora  Arantii  are  said  to  fill  up  the  small  space  that 
would  otherwise  be  left  in  the  axis  of  the  canal  by  the  meeting 
of  the  circular  valves ;  but  these  bodies  are  frequently  indistinct 
in  the  pulmonary  artery,  and  rarely  project  beyond  the  free 
margins  of  the  valves.  Behind  the  valves,  at  the  commencement 
of  the  artery,  are  three  dilations  or  pouches,  bounded  below  by 
the  valves  themselves,  and  called  the  sinuses  of  Valsalva. 

From  the  inner  surface  of  the  ventricular  walls  project  the 
fleshy  columns,  or  carneoe  columnce.  They  are  of  three  kinds, 
attached  by  their  external  surface  and  extremities,  their  internal 
surfaces  being  free,  forming  prominent  ridges,  sometimes  dividing 
and  subdividing.  One  variety,  three  or  four  in  number,  terminate 
in  short  blunt  processes,  and  constitute  the  musculi  papillares, 
whence  the  chordae  tendinese  spring.  These  carneae  columnae 
form  an  intricate  network  on  the  inner  surface  of  the  ventricle, 
occasionally  crossing  the  cavity,  and  forming  what  are  called  the 
moderator  bands.  A  very  well  developed  one  crosses  the  middle 
of  the  cavity  from  the  interventricular  septum  to  the  outer  wall ; 
this  is  termed  the  great  moderator  hand,  and  is  said  to  be 
especially  well  marked  in  "  running  "  animals. 

LEFT   AURICLE. 

The  blood,  after  being  purified  in  the  lungs,  re-enters  the 
heart  at  the  left  auricle,  which  is  smaller  than  the  right,  but  its 
walls  are  thicker.      It  is  situated  at  the  left  postero-superior  part 


LEFT    VENTRICLE. 


393 


<cf  the  heart,  and  consists  of  two  parts,  a  sinus  and  auricular 
<i]ypendix.  The  sinus  is  separated  from  the  right  one  by  the 
interauricular  septum.  The  appendix  is  longer,  narrower,  more 
serrated  than  the  right  one,  and  constricted  at  its  junction  with 
the  sinus.  It  runs  along  the  left  side  of  the  origin  of  the 
pulmonary  artery,  which  helps  to  separate  it  from  the  right 
auricle. 

On  laying  open  the  cavity,  we  find  the  openings  of  the  pul- 
nionnry  veins,  usually  two  pairs,  one  pair  on  the  right,  the  other 
ou  the  left  of  the  sinus  ;  they  are  not  guarded  by  valves.  The 
-remaining  opening  in  the  left  auricle  is  the  auriculo-ventricular, 
which  occupies  the  floor,  and 
communicates  with  the  left 
ventricle,  its  upper  margin 
being  surrounded  by  a  white 
tendinous  ring.  The  obliter- 
ated foramen  ovale  on  the 
septum  is  indistinct.  The 
inner  surface  of  this  auricle 
is  smoother  than  that  of  the 
other,  the  musculi  pectinati 
fewer,  and  confined  to  the 
appendix.  The  appendix 
communicates  with  the  sinus 
through  a  round  constricted 
opening. 


LEFT   VENTRICLE. 


Fig.  1 


Left  side  of  the  heart— laid  open.  1,  Left  ven- 
tricle ;  a  a.  External  wall  ;  b,  Carneae  columnse  ; 
c,  Moderator  band  ;  d  d  d,  Mitral  valve  ;  d'  d', 
Chordae  tendinese  ;  2,  Left  auricle  ;  a  a,  Musculi 
pectinati ;  b.  Openings  of  pulmonary  veins. 


The  blood  leaving  the  left 
auricle  enters  the  left  ventricle, 
which  is  conical,  and  occupies  the  posterior  left  region  of  the 
heart.  It  is  larger,  rounder,  and  more  prominent  than  the 
right,  extending  from  the  auricle  to  the  apex,  which  it  occupies, 
projecting  lower  than  the  right  ventricle.  The  external  wall  is 
much  thickei^than  that  of  the  right  side,beii!ig  thickest  iu  the  centre. 
After  death  the  walls  of  this  cavity  remain  apart,  those  of  the 
right  collapsing ;  on  laying  open  the  cavity  (by  an  incision  close 
upon  the  anterior  furrow,  from  the  apex  to  near  the  origin  of  the 
aorta,  and  another  upon  the  posterior  furrow,  the  two  meeting  at 
the  apex),  two  openings  present  themselves,  the  left  auriculo- 
ventricular  and  the  aortic.      The  left  auriculo-ventricular  open- 


394  ANGIOLOGT. 

ing  resembles  the  right  in  structure,  and  is  guarded  by  a  valve 
with  two  cusps,  the  bicuspid  or  viitral  valve.  The  cusps  consist 
of  doublings  of  the  lining  membrane,  strengthened  with  fibrous 
tissue,  and,  it  has  been  said,  by  muscular  fibre.  One  cusp  rests 
between  the  auriculo-ventricular  and  aortic  openings ;  the  other, 
larger  and  freer,  is  opposite.  They  surround  the  opening,  their 
sides  being  attached  for  a  short  distance,  their  apices  separate. 
The  musculi  papillares  of  the  left  side  are  two,  corresponding  to 
the  valve  segments ;  they  are  large  and  prominent,  one  anterior, 
the  other  posterior.  The  chordae  tendinese  are  few,  longer,  and 
more  powerful  than  those  of  the  right  side  ;  they  are  attached 
to  the  flaps  in  a  similar  manner,  and  spring  from  the  musculL 
papillares. 

The  aortic  oj^ening  is  deeply  situated  in  the  supero-anterior 
part  of  the  ventricle,  a  little  to  the  right  of  the  auriculo-ventricular 
opening,  from  which  it  is  separated  by  one  of  the  segments  of  the 
mitral  valve.  It  is  guarded  by  three  semilunar  valves,  which 
are  similar  in  shape  and  appearance  to,  but  thicker  and  stronger 
than,  those  of  the  right  side  ;  the  corpora  Arantii  are  larger  and 
better  developed,  the  sinuses  of  Valsalva  deeper.  From  two  of 
the  latter  spring  the  coronary  arteries,  which  supply  the  substance 
of  the  heart  with  blood. 

The  septum  of  the  ventricles  is  triangular  in  shape,  and 
extends  to  the  apex  of  the  heart.  It  is  thick  at  the  base, 
thinner  at  the  apex  ;  convex  in  the  right  ventricle,  concave  in 
the  left. 

STRUCTURE    OF    THE    EEART. 

The  heart  consists  of  a  fibrous  framework,  muscular  and  con- 
nexjtive  tissue,  vessels,  and  nerves,  theVhole  being  covered  by  one, 
and  the  cavities  lined  by  another,  serous  membrane.  The  fibrous 
framework  consists  of  fibro- cartilaginous  rings  placed  around 
the  auriculo-ventricular  and  arterial  openings,  extending  within 
the  doubling  of  lining  membrane  which  forms  the  valves  and 
chordse  tendinese  ;  they  are  strongly  developed  on  the  left  side. 
The  auriculo-ventricular  rings  divide  the  heart  into  two  distinct 
parts,  an  auricular  and  ventricular;  they  are  thicker  on  th«ir  lower 
edge,  whence  spring  the  muscular  fibres  of  the  ventricles,  the 
mitral  and  tricuspid  valves,  while  from  the  upper  edge  arise  the 
muscular  fibres  of  the  auricles.  The  right  margin  of  the  left 
auriculo-ventricular  ring  is  connected  with  the  ring  surrounding 


SrfiUCTUEE    OF    THE    HEART. 


395 


the  aortic  opening.  Between  the  aortic  ring  and  auriculo-ven- 
tricular  opening  is  a  fibro-cartilaginous  mass,  connected  with  the 
several  rings,  to  which  muscular  fibres  are  attached,  and  which  in  the 
Ruminant  is  replaced  by  a  triangular  bone  or  os  cordis.  A  second 
bone  is  sometimes  found  between  the  pulmonic  and  auriculo- 
ventricukr  rings.  The  arterial  rings  gird  the  arterial  openings, 
and  serve  for  the  attachment  of  the  vessels,  semilunar  valves,  and 
some  of  the  ventricular  muscular  fibres.  They  seem  to  consist 
of  three  semilunar  portions  united,  which  gives  them  a  festooned 
border,  to  which  is  attached  the  middle  coat  of  the  artery.  The 
other  edge  is  straight,  affording  attachment  to  the  muscular 
fasciculi  of  the  ventricles. 

The  mass  of  the  heart  is  composed  of  muscular' fibres,  con- 
nected by  filamentous  areolar  tissue.  These  fibres  are  involuntary, 
and  of  a  deep-red  colour,  differing  from  other  involuntary  muscles, 
the  oesophagus  excepted,  in  being  transversely  and  longitudinally 
striated.  They  are  smaller  than  voluntary  fibres,  and  are  anasto- 
matic. 

The  muscular  fibres  of  the  auricles  are  separable  into  super- 
ficial and  deep  ;  the  former  common  to 
both  auricles,  the  latter  proper  to  each. 
The  superficial,  common,  or  transverse 
fibres  surround  the  base  of  the  auricles, 
and  are  most  abundant  on  their  anterior 
part.  They  cross  from  one  auricle  to  the 
other,  diverging  to  enclose  the  appen- 
dices and  the  openings  of  the  large  veins. 
They  are  also  prolonged  into  the  inter- 
auricular  septum,  to  assist  in  forming  the 
circular  band  which  surrounds  the  fossa 
ovalis.  The  deep  fibres  proper  to  each 
auricle  consist  of  two  sets,  looped 
and  annular,  which  are  superficial  where  the  external  circular 
fibres  are  deficient.  The  looped  fibres  are  attached  by  their 
extremities  to  the  auriculo-ventricular  tendinous  rings  ;  passing 
over,  they  embrace  each  auricle,  forming  right  and  left  loops. 
The  annular  fibres  are  arranged  in  rings,  forming  a  continuous 
layer.  They  abound  most  in  the  appendices,  and  around  the 
coronary  sinus  and  pulmonary  veins,  extending  .some  distance 
along  the  course  of  the  latter,  and  of  the  cavse. 

Like  the  muscular  fibres  of  the  auricles,  those  of  the  ventricles 


Fig.  152. 
Muscular  fibres  from  the  heart 
of    the  Horse.      Magnified   310 
diamrs. 


396  ANGIOLOGY. 

are  arranged  in  two  sets,  one  common  to  both,  and  another  proper 
to  each  ventricle,  thus  forming  as  it  were  two  muscular  sacs 
enclosed  in  a  third.  The  fibres,  whether  common  or  proper,  are 
attached  directly  or  indirectly  by  both  extremities  to  the  tendin- 
ous rings.  The  common  fibres  are  arranged  in  successive  layers, 
arising  from  the  auriculo-ventricular  ring.  They  extend  spirally 
from  above  downwards,  on  the  anterior  surface  from  right  to  left, 
on  the  posterior  from  left  to  right.  They  are  thin  and  broad  at 
the  upper  pert  of  the  ventricles,  becoming  thick  and  narrow  as 
they  reach  the  apex,  where  they  encoil,  forming  a  whorl,  then 
penetrate  beneath  the  layers,  and  pass  up  internally,  forming  the 
walls  and  septum,  terminating  on  the  auriculo-ventricular  ring. 
The  common  fibres  thus  form  a  superficial  layer,  passing  down- 
wards, and  a  deep  layer  reflected  upwards,  between  which  are 
enclosed  the  layers  special  to  each  ventricle.  The  special  fibres 
form  circular  or  curved  bands,  inserted  by  both  extremities  to  the 
tendinous  rings. 

The  heart  is  supplied  with  blood  by  the  coronary  arteries, 
which  arise  from  the  sinuses  of  Valsalva.  The  blood  is  returned 
by  the  coronary  veins  which  pass  to  the  coronary  sinus,  and  the 
venae  cordis  minimse,  which  terminate  in  the  foramina  Thebesii. 
The  nerves  of  the  heart  come  chiefly  from  the  cardiac  plexus, 
formed  by  the  sympathetic  and  the  vagus.  The  lymphatics 
follow  the  course  of  the  blood-vessels,  and  terminate  in  glands  at 
the  base  of  the  heart. 


ENDOCARDIUM. 

The  cavities  of  the  heart  are  all  lined  by  the  serous  endocar- 
dium, which  is  continuous  with  the  lining  membrane  of  the  blood- 
vessels. It  is  thin,  smooth,  and  glistening,  giving  a  polished 
appearance  to  the  inside  of  the  heart,  to  which  it  adheres  by 
cellular  tissue.  It  enters  into  the  formation  of  the  valves,  being 
strcDgthened  by  fibrous  and  muscular  tissue  between  its  folds. 
It  is  rather  red  in  colour  on  the  right  side. 

So  far  as  the  heart  itself  is  concerned,  since,  in  the  adult,  the 
right  side  is  separate  from  the  left,  there  are  two  Endocardia,  but 
as  the  lining  membrane  of  the  arteries  is  continuous  through  the 
capillaries  with  that  of  the  veins,  the  two  membranes  ultimately 
form  a  continuous  structure. 


gOUESE    OF    THE    CIRCULATION. 


397 


PERICARDLUM. 

The  pericardium  is  a  fibro-serous  sac,  which  encloses  and  is 
Teflected  over  the  heart,  and  origins  of  the  large  blood-vessels.  It 
consists  of  a  parietal  and  visceral  portion,  and  is  composed  of  two 
membranous  layers  ;  one  external,  dense,  and  fibrous,  the  other 
internal  and  serous.  The  outer  fibrous  layer  enters  into  the 
formation  of  the  sac,  or  free  portion  only  of  the  pericardium, 
having  no  direct  attachment  to  the  heart  itself.  It  is  made  up 
of  fibres,  which  interlace  with  each  other 
and  form  a  sac,  whose  apex  embraces  the 
origins  of  the  larger  blood-vessels,  as  tubular 
prolongations.  The  basal  fibres  of  the 
membrane  sometimes  blend  with  the  dia- 
phragm, and  are  also  attached  to  the  last 
bones  of  the  sternum  and  ensiform  cartilage. 
The  parietal  layer  is  covered  by  the  pleural 
folds  which  form  the  middle  mediastinum. 
The  serous  layer  is  much  larger  than  the 
fibrous,  which  it  lines,  and  is  reflected  over 
the  origin  of  the  blood-vessels,  and  external 
surface  of  the  heart,  thus  forming  a  closed 
sac.  The  reflected  portion  is  often  called 
the  epicardium.  Between  the  parietal  and 
visceral  layers  is  secreted  a  pale,  lubrica- 
ting serous  fluid,  the  liquor  'pericardii. 
'The  pericardium  supports  the  heart,  and 
isolates  it  from  the  other  thoracic  viscera. 


COURSE    OF  THE    CIRCULATION. 


Fig.  153. 
Diagram  of  the  circulation 
in  Mammalia  and  Aves.  a, 
Boundary  of  the  heart,  con- 
taining four  cavities ;  h.  Vena 
cava  (represented  as  single' 
here) ;  c,  Eight  auricle  ;  rf, 
Eight  ventricle  ;  e,  Pulmon- 
arj-  artery  ;  /,  Capillaries  of 
the  lungs  ;  g.  Left  auricle, 
receiving  the  purified  blood 
from  the  pulmonary  vein 
(only  one  shown  here) ;  h. 
Left  ventricle  ;  i,  Aorta  ;  j. 
Somatic  capillaries  convey- 
ing the  blood  again  to  the 
veins. 


We  have  seen  that  the  heart  is  divided 
into  a  right  or  venous,  and  a  left  or  arterial 
portion.  In  tracing  the  circulation  it  matters 
little  where  we  commence,  since  wherever  it  be  we  come  back 
to  the  same  point.  Briefly,  the  following  is  the  course  of  the 
blood : — The  venous  blood  is  carried  into  the  right  auricle  by 
the  anterior  and  posterior  venae  cavse.  It  then  passes  through 
the  right  auriculo-ventricular  opening  into  the  right  ventricle  ; 
thence  through  the  pulmonary  artery  to  the  lungs.  It  returns 
by  the  pulmonary  veins  to  the  left  auricle ;  thence  to  the  left 
ventricle,  which  propels  it  through  the  aorta  and  its  branches 


398  ANGIOLOGY, 

into  the  system  generally  ;  the  veins  returning  it  again  to  the 
heart.  The  circulation  is,  therefore,  double — the  Pulmonary  or 
lesser  being  performed  by  the  right,  and  the  Somatic  or  greater 
circulation  by  the  left  side.  Some  writers  speak  of  the  portal 
and  chylo-poietic  or  visceral  circulation  as  forming  a  third  system, 
but  with  respect  to- the  heart  it  is  not  so,  since  they  are  merely  a 
branch  of  the  somatic  circulation. 


Arteries. 

These  are  tubes  conveying  the  blood  from  the  heart,  a  series 
belonging  to  each  circulation.  The  somatic  and  pulmonary 
arteries  leave  the  heart  each  by  a  single  trunk,  which  subdivides 
and  terminates  in  capillaries,  whence  the  venous  radicles  originate. 
The  volume  of  the  secondary  arteries  exceeds  that  of  the  primi- 
tive trunk,  and  similar  relations  exist,  as  far  as  the  ultimate 
divisions  of  the  artery,  their  inclusive  capacity  increasing  towards 
their  termination.  Arterial  branches  arise  at  variable,  angles, 
and  the  originating  angle  exerts  a  decided  influence  on  the 
velocity  of  the  blood  current.  Blood  passing  froi^  a  primary 
into  a  secondary  vessel  which  arises  from  it  at  a  right  angle,  as 
in  some  branches  from  the  aorta,  must  have  its  speed  slackened ; 
on  the  contrary,  the  velocity  is  little  modified  in  vessels  which 
kave  the  paient  trunk  at  a  very  acute  angle,  as  do  many  of  the 
arteries  of  the  limbs. 

The  large  arteries  are  usually  deep-seated,  occupying  the  cavi- 
ties of  the  trunk  and  the  inner  surfaces  of  the  limbs,  where  they 
are  less  exposed  to  injury.  When  they  pass  over  an  articulation, 
they  are  generally  found  on  the  flexor  side.  In  general,  the 
direction  of  the  larger  arteries  is  straight,  but  in  some  parts  they 
are  tortuous,  as  in  the  stomach,  intestines,  bladder;  tongue,  and 
lips ;  in  fact,  wherever  the  circulation  might  be  impeded  ^  by 
sudden  functional  change  in  the  form  or  volume-  of  the  organ. 
Sometimes  this  tortuosity  is  apparently  for  the  purpose  of  moder- 
ating the  energy  with  which  the  fluid  is  propelled  into  delicate 
structures,  such  as  the  brain  and  testicle  ;  small  arteries  which 
run  amongst  loose  structures  generally  become  tortuous  during 
the  contraction  of  the  left  ventricle. 

Arteries  freely  communicate  with  each  other,  forming  what  are 
termed  anastomoses ;  by  convergence,  where  two  branches  join  at 
an   angle    to    constitute    a    single   trunk,    as   the   cerebro-spinal 


STRUCTURE    OF    ARTERIES.  399 

"branches  to  form  the  basilar  ;  by  inosculation,  where  two  vessels 
of  nearly  equal  size  become  continuous  and  form  an  arch,  from 
which  may  spring  smaller  vessels,  as  in  the  arteries  of  the 
intestines ;  by  transverse  branches,  where  two  collateral  arteries 
are  joined  by  a  small  communicating  branch,  as  between  the 
umbilicals  as  they  approach  the  placenta.  In  the  smaller 
arteries  anastomoses  are  frequent,  forming  a  network  which 
pervades  almost  every  tissue  of  the  body.  This  is  a  point  of 
great  importance,  since  the  circulation  can  be  thus  carried  on 
after  the  main  artery  of  the  region  has  been  obliterated,  blood 
being  conveyed  from  neighbouring  sources  by  the  anastomosing 
arteries,  and  it  is  proved  that  under  such  circumstances  the 
smaller  arteries  of  the  part  increase  in  size. 


STRUCTURE   OF   ARTERIES. 

Arteries  are  dense  and  elastic,  possessing  great  power  of  resist- 
ance. When  empty,  they  are  of  a  pale  buff  colour,  and  preserve 
their  cylindrical  form.  Their  walls  consist  of  three  tunics — an 
internal,  middle,  and  external.  The  internal,  serous,  or  tunica, 
intima,  is  the  thinnest,  and  continuous  with  the  lining  membrane 
of  the  heart.  It  is  made  up  of  two  layers  ;  an  inner,  consisting 
of  a  layer  of  epithelial  scales ;  and  an  outer,  transparent,  whitish,, 
highly  elastic,  and  perforated,  being  known  as  the  fenestrated 
niemhrane  of  Henle.  When  the  artery  is  empty,  it  is  thrown 
into  folds,  longitudinal  in  the  large,  transverse  in  the  small 
arteries ;  and  when  distended,  it  is  smooth  and  glistening.  The 
tunica  inedia,  or  contractile  middle  coat,  is  elastic,  dense,  and 
of  a  yellow  colour,  consisting  of  non-striated  muscular,  and  elastic 
fibres ;  thickest  in  the  larger  arteries,  it  becomes  thinner  ia 
the  smaller.  In  the  largest  arteries  this  coat  is  composed  chiefli/ 
of  elastic  tissue  ;  in  the  smallest  vessels  it  is  almost  entirely 
muscular.  The  tunica  extima,  or  external  coat,  is  made  up  of 
areolar  tissue  and  elastic  fibres,  very  thin  in  the  large,  as  thick 
as  the  middle  coat;  in  the  smaller,  while  in  the  smallest  arteries 
it  is  rudimentary  or  wanting.  The  external  surface  is  loose,  and 
connected  by  laminae  with  the  sheath. 

The  arterial  sheaths  consist  of  cellular  tissue,  intimately  con- 
aected  with  the  surrounding  textures.  The  artery  has  only  a 
loose  attachment  to  the  sheath,  so  as  to  allow  of  free  gliding  on 
its  inner  surface.      An  artery  is  usually  accompanied  by  a  vein. 


400  ANCJIOLOGY. 

sometimes  ty  two  veins,  and  generally  by  a  nerve,  all  of  which 
may  lie  in  the  same  sheath,  the  veins  being  usually  more  super- 
-ficial.  The  coats  of  arteries  are  supplied  with  nutrient  blood- 
vessels, the  vasa.  vasorwm,  which  come  from  neighbouring  vessels, 
and  ramify  in  the  external  tunic  ;  they  can  occasionally  be  traced 
into  the  middle  tunic.  Arteries  are  also  provided  with  absorbents, 
which  are  only  visible  on  the  larger  trunks ;  and  plentifully 
supplied  with  nerves,  chiefly  by  the  sympathetic,  \7hich  form 
plexuses  on  the  larger  vessels.  The  external  coat  is  very  tough, 
while  the  middb  and  internal  are  elastic  and  brittle.  On 
ligaturing  an  artery,  the  internal  and  middle  coats  give  way, 
while  the  external  one  is  left  unbroken.  From  the  power  of 
resistance  possessed  by  the  external  coat,  we  are  enabled  to  stop 
haemorrhage  by  torsion ;  the  middle  and  internal  coats  giving 
way,  the  external,  which  remains  unbroken,  forms  a  spiral  ligature 
round  the  others,  so  tight  that  it  cannot  be  unravelled  by  twisting 
in  an  opposite  direction. 

CAPILLARIES. 

The  smaller  arteries  terminate  in  a  system  of  minute  vessels — 
the  cajnllaries — which  are  interposed  between  the  termination  of 
the  arteries  and  the  commencement  of  the  veins,  forming  plexuses 
which  vary  much  in  arrangement.  Their  average  diameter  is 
about  a^oVo*^  ^^  ^^  inch,  varying  in  different  textures,  smallest 
in  the  brain  and  raucous  membrane  of  the  intestines,  largest  in 
the  skin,  in  glands,  and  the  interior  of  bones.  All  arteries  do 
not  terminate  in  capillaries,  an  exception  being  in  erectile  tissue, 
where  the  arteries  end  in  cells  or  cavities  placed  at  the  origin  of 
the  veins. 

PULMONARY   ARTERY. 
(Fig.  154./.) 

The  pulmonary  artery  springs  from  the  conus  arteriosus  of  the 
right  ventricle,  its  origin  being  guarded  by  the  sigmoid  valves  ; 
it  curves  upwards  and.  backwards  until  it  reaches  the  upper  part 
of  the  left  auricle,  where  it  divides  into  right  and  left  branches, 
which  penetrate  the  substance -of  their  respective  lungs,  along 
with  the  bronchi,  ramifying  in  the  substance  along  with  the 
bronchial  tubes,  and  terminating  by  capillary  branches,  which 
form  a  dense  network  on  the  walls  of  the  air-cells ;  the   branches, 


EXPLANATION  dF  PLATE  V 


Blood- Vascular  System  of  the  Horse. 


1.  Heart,  right  ventricle 

18.  Coeliac  axis. 

2.  Heart,  left  ventricle. 

19.  Mesenteric  arteries. 

3.  Heart,  left  auricle. 

20.  Renal  artery  (left). 

4.  Pulmonary  artery. 

21.  Small  testicular  artery. 

5.  Pulmonary  veins. 

22,  Posterior  vena  cava. 

6.  Anterior  aorta. 

23.  Portal  vein. 

7.  Carotid  artery. 

23'.  Hepatic  circulation. 

8  8.  Glosso-facial  artery. 

24.  External  iliac  artery. 

.9.  Left  brachial  artery. 

25.  Internal  iliac  artery. 

10.  Dorsal  artery. 

26.  Lateral  sacral  artery. 

11.  Superior  cervical  artery. 

27.  Femoral  artery. 

12.  Vertebral  artery. 

28.  Posterior  tibial  artery. 

12'.  Internal  thoracic  artery. 

28'.  Ajiterior  tibial  artery. 

13,  Humeral  artery. 

28".Femoro-popliteal  artery. 

14.  Radial  artery. 

29.  Metatarsal  vessels. 

14'.  Cubital  artery. 

30.  Venous  plexus  of  the  foot 

15.  Great  metacarpal  artery. 

31.  Internal  saphenic  vein. 

16,  Ungual  branches. 

32.  Cephalic  vein. 

17.  Posterior  aorta. 

33.  Jugular  vein. 

CORONARY   ARTERIES.  401 

"belonging  to  different  lobules  do  not  anastomose ;  from  these 
capillaries  spring  the  radicles  of  the  pulmonary  veins.  The 
pulmonary  artery  at  its  origin  is  joined  by  its  right  side  to  the 
aorta,  round  which  it  winds,  both  vessels  being  enclosed  in  a 
serous  tube,  formed  by  a  continuation  of  the  visceral  layer  of  the 
pericardium  ;  above  this  is  attached  the  fibrous  layer  of  the  samo 
membrane,  which  is  carried  onwards  for  a  short  distance  as  a 
tubular  sheath.  About  its  centre,  this  artery  is  united  to  the 
posterior  aorta  by  a  short,  dense,  fibrous  cord,  the  remains  of  the 
foetal  ductus  arteriosus  ;  its  walls  are  thinner  than  those  of  the 
aorta.  The  pulmonary  is  the  only  artery  in  the  adult  that 
conveys  venous  blood. 

COMMON    AORTA. 

(Fig.  154.  e.) 

The  common  or  primitive  aorta  is  the  main  trunk  of  the 
arterial  system.  It  arises  from  the  antero-superior  part  of  the  left 
ventricle,  being  attached  to  the  aortic  fibrous  ring,  and  guarded 
by  the  sigmoid  valves  ;  it  passes  upwards  and  forwards  for  nearly 
two  inches,  then  divides  into  two,  the  anterior  and  posterior 
aortoi,  the  former  supplying  the  fore  extremity,  neck,  and  head, 
the  latter  the  rest  of  the  body,  and  limbs.  The  aorta  has  on  its 
right  side  the  right-  auricle,  and  on  its  left  the  pulmonary  artery, 
to  which  it  is  joined  by  cellular  tissue,  the  two  lying  in  one 
sheath.     The  trunk  is  traversed  by  the  cardiac  nerves, 

CORONARY  ARTERIES. 

(Fig.  154.  d.) 

In  addition  to  its  terminal  divisions,  the  aorta  gives  off  the 
right  and  left  coronary,  or  cardiac  arteries,  each  of  which  arises 
from  one  of  the  sinuses  of  Valsalva  ;  thence  the  right  one  passes 
to  the  right  of  the  pulmonary  artery,  under  the  right  auricle,  and 
along  the  auriculo-ventricular  furrow  ;  Oi.  reaching  the  right  longi- 
tudinal furrow,  it  divides  into  vertical  and  transverse  branches. 
The  vertical  descends  the  right  longitudinal  furrow,  yielding 
branches  to  the  ventricular  walls,  rounds  the  apex,  and  anasto- 
moses by  convergence  with  the  corresponding  left  branch  ;  the 
small  transverse  branch  passes  along  the  transverse  furrow,  anasto- 
mosing with  its   fellow.     The  left  coronary  artery  arises   as  the 

2d 


402 


ANGIOLOGY. 


right,  passing  out  behind  and  between  the  pulmonary  artery,  and 
the  apex  of  the  left  auricular  appendix,  and  immediately  divides 
into  vertical  and  transverse  branche?,  with  a  distribution  similar 
to  that  of  the  right  one. 

We  will  first  consider  the  Posterior,  afterwards  the  Anterior 
Aorta. 

POSTERIOR   AORTA, 
f  Plate  V.  17.) 

The  posterior  aorta  is  larger  and  longer  than  the  anterior.     It 


Fig.  154. 
Thorax  opened  on  the  left  side— showing  the  heart  and  large  vessels  in  situ,  a  a,  Pericardial  sac't 
b,  Left  Tentricle  ;  c,  Eight  ventricle  ;  d,  Left  coronary  artery  :  e,  Primitive  or  common  aorta  ;  «', 
Anterior  aorta  ;  e",  Posterior  aorta  ;  /,  Pulmonary  artery,  divided  and  ligatured  ;  g.  Anterior  vena 
cava  ;  h.  Posterior  vena  cava  ;  i,  Right  bracial,  or  brachio-cephaUc  artery  ;  k,  Left  brachial  artery  ; 
I,  Left  dorsal  artery,  giving  off  the  subcostal  posteriorly ;  m.  Left  superior  cervical  artery  ;  n,  Left 
vertebral  artery  ;  o,  Left  inferior  cervical  artery  ;  p,  Left  external ;  and  o,Internal  thoracic  arteries. 

commences  at  about  the  level  of  the  fourth  dorsal  vertebra, 
passes  upwards  and  backwards,  forming  the  aortic  arch,  and  reach- 
ing the  left  sjde  of  the  spine  at  the  sixth  or  seventh  dorsal  ver- 
tebra. It  passes  straight  backwards  to  the  hiatus  aoiticus,  entering 
the  abdomen  between  the  pillara  of  the  diaphragm,  and  terminal- 


PAEIETAL    BRANCHES.  403 

ing  in  the  posterior  part  of  the  sublumbar  region  by  breaking  up 
into  the  external  and  internal  iliacs.  It  is  divided  into  thoracic 
and  abdominal  portions.  The  arch  of  the  thoracio  portion  is 
crossed  on  the  right  by  the  trachea  and  oesophagus,  having  the 
pulmonary  artery  on  the  left ;  along  the  spine  it  lies  in  the  pos- 
terior mediastinum,  related  on  the  right  with  the  vena  azygos  and 
the  thoracic  duct.  The  abdominal  portion  is  embraced  by  twigs 
of  the  sympathetic  nerve,  and  related  with  the  reservoir  of  Pecquet 
above,  and  the  posterior  vena  cava  on  its  right.  The  posterior 
aorta  furnishes  parietal  and  visceral  branches,  which  we  tabulate 
as  follows  : — 

PAEIETAL  BRANCHES. 

Aortic  intercostal,  I  Phrenic. 

Liimbar,  I  Middle  sacral. 

The  Intercostal  arteries  are  doublets,  seventeen  in  number, 
the  last  thirteen  of  which,  the  aortic  intercostals,  arise  directly 
from  the  posterior  aorta  ;  while  the  first  arises  from  the  superior 
cervical,  the  next  three  from  the  dorsal  artery.  The  aortic  inter- 
costals leave  the  superior  part  of  the  trunk  at  right  angles,  skirt 
the  dorsal  vertebrse,  and  at  the  upper  margin  of  the  intercostal 
spaces  divide  into  inferior  or  intercostal,  and  superior  or  dorso- 
spinal.  The  intercostal  branch  is  the  larger,  and  travels  along 
the  grooved  posterior  border  of  the  rib  down  the  side  of  the 
thorax,  associated  with  the  vein  and  nerve.  These  arteries 
anastomose  with  the  asternal,  and  anterior  abdominal  branches 
of  the  internal  thoracic ;  while  the  last  four  traverse  the 
abdominal  muscles,  and  anastomose  with  the  abdominal  and 
circumflex  ilii.  The  intercostal  branch  supplies  the  pleura, 
intercostal,  and  thoracic  muscles.  The  dorso-spinal  branch  is 
distributed  to  the  dorsal  muscles  and  integument,  supplying  the 
spinal  cord  and  its  coverings  through  the  intervertebral  foramen. 

The  LUMBAK  arteries,  five  or  six  pairs,  originate  like  the  inter- 
costals, dividing  in  the  intertransverse  spaces  into  superior  or 
luniho-spinal,  the  larger,  which  are  distributed  to  the  muscles 
and  integument  of  the  loins,  furnishing  spinal  branches  to  the 
cord  and  its  membranes  ;  and  inferior,  which  pass  to  the  psoe, 
transyersalis  abdominis,  and  internal  oblique  muscles,  and  there 
anastomosfe  -with  the  circumflex  ilii.  The  last  lumbar  may  arise 
from  the  internal  iliac  artery  (Fig.  158.  1,  1). 

The  Phrenic  or  Diaphrag]matic  arteries  are  usually  two  or 


404  ANGIOLOGY. 

three  small  vessels  which  arise  at  thd  hiatus  aorticus ;  one  goes 
to  the  left,  the  other  to  the  right  diaphragmatic  crus,  terminat- 
ing on  the  phrenic  centre.  The  right  gives  twigs  to  the  pleura 
and  right  lung. 

The  Middle  Sacral  artery  is  a  single  mesian  continuation  of 
the  posterior  aorta.  Large  in  some  animals,  when  present  in  the 
horse  it  is  extremely  rudimeotary,  and  it  is  often  absent. 


VISCERAL   BRANCHES. 

Broncho-cesophageal. — Thoracic 

Coeliac  axis. 

Great  mesenteric. 

Small  mesenteric.         >    .  ,  ,      .     , 
_,       ,  >  Abdommal. 

Renal. 

Spermatic. 

Small  testicular. 

The  BrOnchO- (ESOPHAGEAL  arises  close  to  and  sometimes  with' 
the  first  pair  of  aortic  intercostals,  breaking  up  into  bronchial 
and  oesophageal  branches.  The  bronchial  arteries  pass  between 
the  aortic  arch  and  the  oesophagus,  to  the  bifurcation  of  the 
trachea,  dividing  into  right  and  left,  which  enter  the  lungs  with 
the  bronchi,  ramifying  with  the  air-tubes,  and  terminating  in  the 
pulmonary  capillaries.  The  oesophageal  artery  proceeds  back- 
wards to  the  posterior  mediastinum  ;  reaching  the  oesophagus,  it 
divides  into  two.  The  large  superior  one  is  distributed  to  the 
upper,  the  inferior  to  the  linder  surface,  ^nastomosii^g  Avith  the 
pleural  branch  of  tbe  gastric,  and  supplying  the  posterior 
mediastinum. 

CCELIAC   AXIS. 
(Fig.  155.  1.) 

This  is  a  short  trunk  arising  from  the  lower  surface  of  the 
aorta  as  it  enters  the  abdomen.  About  an  inch  in  length,  it 
divides  into  the  gastric,  splenic,  and  hepatic  arteries. 

The  Gastric,  the  central  and  smallest  division,  passes  the 
cardiac  orifice  of  the  stomach,  and  divides  into  right  or  anterior, 
left  or  posterior,  and  pleural ;  the  latter  enters  the  thorax  by  the 
foramen  siuistrum,  bifurcates  and  anastomoses  with  the  oesophageal 
and  superior  branches  of  the  thoracic  artery.  The  right  gastric 
passes  to  the  oesophagus  over  the  lesser  curvature  of  the  stomach. 


CCELIAC   AXIS. 


405 


and  is  distributed  to  the  anterior  aspect  of  the  greater  cul-de-sac ; 
the  left  gastric  gains  the  posterior  aspect,  and  ramifies  over  the 
right  cul-de-sac ;  both  are  tortuous,  and  anastomose  with  each 
other  and  with  the  splenic  artery. 

The  Splenic  artery,  the  largest  coeliac  division,  passes  to  the 
left,  over  the  fundus  of  the  stomach,  and  enters  the  hilus  of  the 


Abdominal  branches  of  the  posterior  aorta- .^the  left  abdominal  wall  and  diaphragm,  small  intes- 
tine and  great  colon  being  removed.  I,  Aorta  ;  II,  Liver  ;  III,  Stofnach  ;  IV,  Spleen  ;  V,  Left 
kidney;  VI,  Floating  colon:  1,  Coeliac  axis;  a,  Gastric  artery;  a'.  Its  anterior,  and  o".  Its 
posterior  branch;  a'",  Pleural  artery;  6  h,  Hepatic  artery ;.  6' 6',  Pyloric  artery;  6",  Duodenal 
artery ;  6"',  Right  gastro-epiploic  artery  ;  c,  Splenic  artery  ;  d.  Pancreatic  branch ;  c"  c",  Small 
branches  to  the  stomach  ;  c'",  Left  gastro-epiploic  artery  ;  2,  Anterior  mesenteric  artery  divided  ; 
3,  Left  renal  artery  ;  4,  Left  spermatic  artery  divided ;  5,  Posterior  mesenteric  artery  ;  d  d.  Its 
radiating  branches  ;  d'  d'  d'.  Their  inosculatory  arches  ;  d",  Hasmorrhoidal  branch  ;  6  6,  Lumbar 
arteries  ;  e  e,  Their  spinal  branches. 

spleen,  enveloped  in  the  gastro-splenic  omentum  ;  at  the  splenic 
apex  it  becomes  the  left  gastro-epiploic,  which  passes  along  the 
greater  curvature  of  the  stomach  as  far  as  the  lesser  cul-de-sac, 
finally  anastomosing  with  the  right  gastro-epiploic  branch  of  the 
hepatic  artery  ;  it  supplies  the  spleen  and  stomach,  and  gives  a 
small  twig  to  the  pancreas. 

The  Hepatic  artery  passes  to  the  right,  partly  embedded  in 


406 


ANGIOLOGY. 


the  pancreas,  crosses  obliquely  under  the  posterior  vena  cava, 

and  entering  the  trans- 
verse fissure  of  the  liver, 
is  distributed  to  that 
organ,  along  with  the 
vena  porta;  it  supplies 
the  substance  of  the  liver, 
in  which  organ  its  ulti- 
mate branches  form  three 
communicating  series,  to 
which  the  following  terms 
have  been  applied  :  the 
rami  vasculares,  which 
supply  the  walls  of  the 
bile  ducts  and  blood  ves- 
sels, as  vasa  vasorum ; 
the  rami  capsulares, 
which  supply  the  capsule; 
and  the  rami  lohulares 
supplying  the  substance 
of  the  lobules.  The 
hepatic  artery  gives  off 
'pancreatic  twigs  to  the 
pancreas,  and  i\Le  pyloric, 
which  passes  over  the 
duodenum  to  the  pylorus 
and  lesser  curvature  of 
the  stomach,  anastomos- 
ing with  the  left  gastric. 
The  hepatic  artery  also 
gives  off  the  right  gastro- 
epiploic and  duodenal. 
The  former,  crosses  the 
duodenum,  gains  the 
greater  curvature  of  the 
stomach,  and  inosculates 
with  the  left  gastro- 
epiploic ;  the  latter  pro- 
ceeds along  the  curvature 
of   the    duodenum,    and 

anastomoses  with  a  branch  of  the  great  mesenteric  artery. 


Fig.  156. 
Arteries  of  the  ceecum,  colon,  and  part  of  the  floating 
colon.  I,  Trunk  of  the  great  mesenteric  artery  •  a,  Anas- 
tomotic artery  of  the  floating  colon  ;  6  b  6,  Left  colic 
artery  ;  V,  Pancreatic  branch  ;  cec.  Right  colic  artery  ; 
d,  Inosculation  of  the  two  colic  arteries ;  «,  Ileo-csecal 
artery. 


LESSER  MESENTERIC  ARTERY.  407 

GREAT  MESENTERIC  ARTERY. 

(Fjg.  155,  2.) 

The  anterior  or  great  mesenteric  artery  arises  a  little  behind 
the  coeliac  axis,  and  splits  into  left,  right,  and  anterior  divisions. 
The  left  consists  of  a  score  or  so  of  branch  lets,  which  pass  to  the 
mesentery,  being  arranged  in  a  radiating  -manner  between  its 
folds,  and  inosculating  with  each  other  near  the  lesser  curvature 
of  the  small  intestine,  so  forming  arches,  from  which  twigs 
proceed  to  the  intestine.  The  first  of  these  branches  anastomoses 
with  the  duodenal  branch  of  the  hepatic. 

The  right  division  divides  into  ileo-csecal,  superior  and  inferior 
csecal,  and  right  colic  arteries.  The  ileo-ccBcal  passes  in  the 
mesentery  along  the  ileum,  and  inosculates  with  the  last  branch 
of  the  left  division.  The  superior  or  internal  ccecal  goes  to  the 
upper,  the  inferior  or  external  coical  to  the  lower  fissure  of  the 
caecum ;  as  it  crosses  the  junction  of  the  colon  and  csecum,  it 
supplies  the  artery  of  the  arch  which  winds  partly  round  the 
origin  of  the  colon.  The  right  colic  supplies  the  first  and  second 
portions  of  the  large  colon,  inosculating  with  the  left  colic  at 
the  pelvic  flexure. 

The  anterior  division  consists  of  the  left  colic  or  retrograde, 
and  a  branch  to  the  floating  or  single  colon ;  near  its  origin  it 
gives  off  a  branch  to  the  pancreas.  The  retrograde  runs  parallel 
with  the  right  colic,  inosculating  with  it,  and  supplying 
the  third  and  fourth  portions  of  the  great  colon.  The  artery 
of  the  floating  colon  anastomoses  with  the  posterior  mesenteric 
artery. 

LESSER   MESENTERIC    ARTERY. 

(Fig.  155.  5.) 

The  posterior  or  lesser  mesenteric  artery  originates  at  from 
three  to  four  inches  behind  the  great  mesenteric  ;  longer  but  less 
capacious  than  the  latter,  it  divides  into  thirteen  or  fourteen 
branches,  which  supply  the  floating  colon  and  rectum,  one  branch 
anastomosing  with  the  artery  of  the  floating  colon  from  the 
anterior  mesenteric.  They  lie  in  the  folds  of  the  colic  mesentery, 
and  the  first  eight  form  arches  as  in  the  anterior  mesentery,  but 
the  rest,  which  chiefly  supply  the  rectum,  break  up  singly  without 
forming  arches ;  these  are  known  as  the  hcemorrhoidal  arteries. 


408  AlsGIOLOGY. 

The  Renal  arteries,  right  and  left,  leave  the  aorta  at  right 
angles,  almost  corresponding  with  the  anterior  mesenteric  artery  ; 
the  right,  having  to  cross  the  vena  cava,  is  the  longer.  They  pass 
straight  to  the  hilus  of  the  kidney.  Reaching  the  limiting  layer, 
they  break  up  and  form  the  capillary  network,  and  Malpighian 


i-io.  157. 
Breaking  up  of  the  posterior  aorta— the  pelvis  being  opened  on  the  left  side. 
1,  Spermatic  cord  divided  ;  2,  Septum  scroti ;  3,  Penis  ;  4,  Bladder  ;  5,  Left 
Tesicula  seminalis  ;  0,  Rectum.  Ar.TEBiEs— A,  Posterior  aorta  ;  a.  Spermatic  ; 
h,  Kxternal  iliac  ;  h',  Circumflex  ilii  ;  h"  h'" ,  Branches  to  iliac  glands  ;  h"". 
Small  testicular;  c,  Prepubian ;  c',  Epigastric;  c" ,  External  pubic;  B  B, 
Internal  iliacs  ;  d,  Left  ilio-lumbar  ;  e,  Common  Origin  of  umbilical  and 
Internal  pudio  ;  e',  tTmbilical ;  e".  Internal  pudic ;  /,  Lateral  sacral;  g,  Right 
Ilio-lumbar  ;  h.  Gluteal  ;  i,  Iliaco-femoral  ;  k.  Obturator. 

tufts  (see  Kidney).      An  anterior  branch  supplies  the  suprarenal 
capsule. 

The  Spermatic  arteries,  right  and  left,  become,  in  the  female, 
the  utero-ovarian.  They  spring  from  the  under  surface  of  the 
posterior  aorta,  near  the  posterior  mesenteric,  it  may  be  behiod. 


INTERNAL    ILIAC    ARTERY.  40 & 

on  a  level  with,  or  before  it,  and  they  may  both  arise  in  common. 
The  spermatic,  their  diameter  considered,  are  the  longest  arteries 
in  the  body ;  they  pursue  a  diverging  course  through  the 
inguinal  canal,  and  become  a  constituent  of  the  spermatic  cord, 
lying  on  its  anterior  border ;  as  they  near  tlie  testicle  they 
become  extremely  tortuous,  and  are  finally  distributed  to  the 
tunica  vasculosa. 

The  Utero-ovarian  artery  passes  to  the  broad  ligament  of  the 
uterus,  dividing  into  ovarian  and  uterine  branches.  The  former 
is  tortuous,  supplying  the  ovary ;  the  latter  passes  to  the  cornu 
of  the  uterus,  anastomosing  with  the  uterine  artery. 

The  Small  testicular,  or  Artery  of  the  cord,  is  small, 
and  sometimes  arises  from  the  aorta,  between  the  internal  and 
external  iliac  arteries,  or  it  may  arise  from  the  latter,  far  down. 
It  passes  through  the  inguinal  canal,  and  supplies  the  tissues  of 
the  cord,  first  giving  twigs  to  the  ureter,  vas  deferens,  and  peri- 
toneum. In  the  female,  this  artery  becomes  the  Uterine,  which 
is  much  larger,  and  is  distributed  to  the  body  and  cornu  of  the 
uterus,  anastomosing  with  the  utero-ovariaa  and  vaginal  arteries. 

The  posterior  aorta  at  the  level  of  the  last  lumbar  vertebra 
gives  off  the  External  Iliac  arteries,  and  a  little  po.sterior  to  this 
the  rest  of  its  trunk  bifurcates,  forming  the  Internal  Iliac  arteries. 
These  four  vessels  are  all  large,  and  their  origins  are  so  near 
together  that  the  breaking  "dp  of  the  aorta  has  been  termed  the 
iliac  quadrifurcation. 

INTFiM'TAL    ILIAC    ARTERY.- 

(Fig.  157.  B  B.  ;  Fig.  158.  C  C.) 

The  internal  iKac  arteries  are  short,  thick  trunks,  extending 
from  the  last  lumbar  vertebra  to  near  the  insertion  of  the  psoas 
parvus.  They  supply  the  pelvic  viscera,-  and  partially  the 
muscles  of  the  Lind  quarter.  Each  of  these  trunks  gives  off  the 
following  arteries  :  — 

Umbilical.  Iliaco-femoral. 

Internal  pudic.  Obturator. 

Ilio-lumbar.  Gluteal. 

Lateral  sacral. 

The  Umbilical  artery,  large  in  the  foetus,  is  a  mere  fibrous 


410 


ANGIOLOGY. 


cord  in  the  adult ;  it  extends  from  the  aorta  to  the  fundus  of  the 
bladder,  inside  the  free  border  of  the  lateral  false  ligament, 
winding  partly  round  the  vas  deferens. 

The  Internal  pudic,  or  Artery  of  the  Bulb,  passes  back- 
wards and  downwards,  related  with  the  supero-lateral  aspect  of 
the  bladder  ;  it  winds  over  the  ischial  arch,  supplying  the  bulb 
and  crura  of  the  penis.      It  gives  off  posteriorly  several  twigs  to 


Fig.  153. 


Distribution  of  the  internal  iliac[aTteri%s— ihe  pelvis  opened  from  the  right  side 
and  the  viscera  removed.  I,  The  tail ;  II,  The  penis  ;  A,  Posterior  aorta  ;  B  B, 
External  iliacs  ;  C  C,  Internal  iliacs  •,  C  Middle  sacral ;  1 1,  Last  lumbars ;  C  2,  Internal 
pudics  cut ;  3  3,  Lateral  sacrals  ;  a  a,  Sicto-spiuals  ;  6  6,  Iliddlo  coccvgeal  ;  c  c,  Lateral 
coccygeals;  d,  Superior  branch  of  same,  e  e,  Ischiaticj ;  i,  Ilio-lumbiW ;  5,  Gluteal; 
6,  lliaco-feraoral ;  /,  Nutrient  artery  of  ilium;  7,  Obturator;  g,  Katrien'..  artery  of 
ischium  ;  h,  Inferior  branch  ;  i,  Cavernous  and  crural  portion. 

Cowper's  gland,  and  anteriorly  the  vesico-prosictic  artery,  which 
gives  a  posterior  branch  to  the  prostate  gland,  an  anterior  one  to 
the  vas  deferens,  and  also  twigs  to  the  buJb  of  the  latter,  to  the 
vesicula  seminalis,  and  walls  of  the  bladder  ;  one  branch  is  the 
perineal  artery  which  passes  the  ischial  arch,  and  supplies  the 
anus  and  urethral  muscle  superiorly.      In  the  female  the  internal 


EXTERNAL    ILIAC    ARTERIES.  411 

pudic  artery  furnishes  branches  to  the  rectum,  vulva,  and  vaginal 
bulb,  together  with  the  analogue  of  the  vesico-prostatic  in  the 
male — the  vaginal  artery,  which  anastomoses  with  the  uterine, 
supplying  also  the  bladder.  The  perineal  artery  in  the  female 
supplies  the  vulva. 

The  Ilio-lumbar  artery  is  given  off  at  a  right  angle,  passing 
between  the  iliacus  muscle  and  the  venter  surface  of  the  ilium. 
It  supplies  the  sacro-iliac  articulation,  the  sublumbar  muscles,  and 
surmounting  the  iliac  crest,  becomes  buried  in  the  gluteus  maximus. 

The  Iliaco-femoral  artery,  large  in  the  horse,  passes  down- 
wards and  outwards,  crossing  the  iliacus,  ,to  supply  the  crural 
triceps  and  tensor  fasciae  latse  from  the  outside. 

The  Obturator  artery  is  sometimes  regarded  as  having  a 
common  origin  with  the  iliaco-femoral,  sometimes,  and  more 
correctly  as  being  given  off  by  the  latter.  It  is  a  long  vessel 
passing  backv-;ards  and  downwards,  along  the  lower  edge  of  the 
pyriformis  muscle,  and  through  the  obturator  foramen,  when  it 
<livides  into  cavernous  and  crural  branches,  the  first  going  to 
the  dorsum,  the  other  to  the  bulb  and  crus  of  the  penis.  It 
gives  en  route  an  inferior  branch  to  the  ischio-tibial  muscles. 

The  Gluteal  artery  is  the  largest  branch  of  the  group,  and 
passes  along  the  pelvig  roof  downwards,  and  through  the  great 
sciatic  notch,  along  with  the  great  sciatic  nerve.  It  supplies  the 
gluteal  muscles,  anastomosing  with  the  ilio-lumbar. 

The  Lateral  sacral  artery  runs  straight  backwards  along 
the  side  of  the  sacrum  near  its  inferior  foramina,  through  which 
it  sends  in  the  sacrospinal  branches  to  supply  the  spinal  cord. 
It  finally  divides  into  ischiatic  and  lateral  coccygeal;  the  former 
winds  outss^ards  behind  the  sacro-sciatic  ligament,  and  breaks  up 
in  the  ischio-tibial  muscles,  anastomosing  with  ascending  twigs 
of  the  femoro-popliteal,  deep  femoral,  and  obturator  arteries. 
The  lateral  coccygeal  branch  is  continued  backwards,  supplying 
the  tail ;  a  middle  coccygeal  branch  is  given  off  usually  from  the 
light  or  left  lateral  sacral  artery,  perhaps  oftener  from  the  left. 

external  iliac  arteries. 

(Fig.  157.  h.) 

These,  the  anterior  or  external  branches  of  the  aortic  quadri- 
furcation,  are  essentially  the  arteries  of  the  pelvic  limb.  Each  of 
them  arises   below   the   last  lumbar  vertebra,  curving  obliquely 


412  ANGIOLOGY. 

outwards  and  downwards.  At  the  level  of  the  ilio-pectineal  line 
it  becomes  the  femoral.  The  external  iliac  artery  gives  off  the 
circumflex  ilii,  and  sometimes,  as  we  have  seen,  the  small  testi- 
cular artery. 

The  Circumflex  Ilii  springs  from  the  outer  side  of  the  iliac 
near  its  origin,  or  occasionally  from  the  aorta,  crosses  the  psoas 
magnus  and  iliacus  towards  the  anterior  iliac  spine,  where  it 
divides  into  two  branches,  an  anterior,  which  ramifies  in  the 
transversalis  and  iuternal  oblique,  anastomosing  with  the  abdo- 
minal branches  of  the  intercostal  and  lumbar  arteries  ;  and  a 
posterior,  which  crosses  the  abdomen  just  below  the  external 
iliac  spine,  between  the  iliacus  and  internal  oblique,  descending 
in  the  tensor  fascise  latse  anteriorly,  and  terminating  in  sub- 
cutaneous twigs, 

FEMORAL    ARTERY. 
(Fig.  159.  1.) 

This  is  the  artery  of  the  thigh,  a  continuation  of  the  external, 
iliac,  extending  from  the  level  of  the  pelvic  brim  to  the  heads  of 
the  gastrocnemius  muscle ;  it  lies  in  the  femoral  space  between 
the  iliacus,  pectineus,  and  sartorius  muscles,  and  is  related  with 
the  internal  saphenic  nerve  and  satellite  vein,  along  the  pectineus 
and  vastus  internus,  and  the  posterior  border  of  the  sartorius  ;  it 
then  enters  a  ring  formed  by  the  two  parts  of  the  adductor  longus 
and  the  femur,  and  passing  between  the  bifid  origin  of  the 
gastrocnemius  muscle  becomes  the  popliteal.  Two  important 
arteries  are  given  off  at  the  point  where  the  iliac  becomes  the 
femoral,  but  are  best  regarded  as  branches  of  the  later,  they  are 
the  prepubian  and  arteria  profunda  femoris  ;  they  ge\ierally  have 
a  common  origin.      The  branches  of  the  femoral  artery  are  : — 

Prepubian.  I  Superficialis  femoris. 

Profunda  femoris.  |  Small  muscular. 

Saphenic. 

The  Prepubian  artery,  a  short  vessel,  arises  in  common  with 
the  arteria  profunda  femoris  at  the  level  of  the  pelvic  brim. 
Crossing  the  crural  ring  it  gains  the  posterior  aspect  of  the 
internal  abdominal  ring,  and  divides  into  the  epigastric  and 
external  pudic.  The  epigaotric  or  posterior  abdominal  artery, 
runs  forwards  between  the  small  oblique  and  transverse  mu&cies, 
a.nd  along  the  border  of  the  rectis  abdominis  and  inner  side  of  the 


FEMORAL    ARTERY. 


415 


internal  abdominal  ring,  thus  crossing  the  spermatic  cord  on  the 
inside.  It  supplies  the  rectus  muscle  and  other  portions  of  the 
abdominal  parietes,  anastomosing  with  the  circumflex  ilii  and 
anterior  abdominal  arteries.  The  external  pudic  artery  descends 
to  the  dorsum  penis, 
through  the  inguinal 
canal,  where  it  becomes 
the  dorsal  artery  of 
the  penis,  and  divides 
into  anterior  and  pos- 
terior. The  anterior 
is  long  and  flexuous, 
so  as  to  allow  protru- 
sion of  the  penis  ;  it 
runs  along  to  the  an- 
terior extremity,  sup- 
plying the  erectile 
tissue.:  The  posterior 
also  passes  to  the 
dorsum,  and  anasto- 
moses with  the  inter- 
nal pudic  and  obtura- 
tor, supplying  the 
scrotum. 

The  external  pudic 
gives  off  the  subcu- 
taneous abdominal 
artery  which  passes 
forwards  through  the 
inguinal  canal,  and 
over  the  abdominal 
fascia,  reaching  the 
anterior  extremity  of 
the  suspensory  liga- 
ment of  the  sheath, 
where  it  terminates 
by  numerous  subcu- 
taneous twigs  supplying  the  skin,  sheath,  and  superficial  inguinal 
glands,  one  twig  circling  round  the  umbilicus  to  inosculate  with 
its  fellow  from  the  opposite  side.  In  the  female,  the  mammary 
replaces  the    dorsal    artery    of    the    penis  ;    it    is    much  largei" 


Fio.  159. 
Internal  viewof  left  thigh— showingthearteries.  1,  Femoral; 
a  a  a.  Profunda  femoris  ;  6,  Superficialis  femoris  ;  c,  Saphenic ; 
ddd  d,  Muscular  branches ;  e.  Femoral  nutrient  vessels  cut- 
(the  femoral  becomes  the  popliteal  at  about  this  point) ;  /, 
Femoro-popliteal ;  /',  Its  muscular  branches  ;  /",  Its  descend- 
ing branch ;  g,  Recurrent  tibial ;  h,  United  trunli  of  saphenic 
and  femoro-popliteal ;  i,  Internal  plantar. 


414  ANGIOLOGY. 

than  the  subcutaneous  abdominal  branch,  and  ramifies  in  the 
substance  of  the  gland  ;  and  as  it  dips  between  the  thighs  it 
sends  a  twig  along  the  perineum  to  the  inferior  commissure  of 
the  vulva. 

The  Arteria  profunda  femoris  arises  witb  the  prepubian  at 
the  origin  of  the  femoral.  Some  regard  it  as  a  bifurcation  of  the 
iliac.  It  passes  directly  backwards  between  the  iliacus  and 
pectineus,  and  over  the  obturator  externus,  gains  the  deep  face 
of  the  adductors,  winds  round  the  femur,  supplying  the  hip  joint 
and  adjacent  muscles,  and  is  lost  in  the  biceps  rotator  tibialis  and 
triceps  adductor  femoris,  anastomosing  with  branches  of  the 
ischiatic  and  obturator  arteries. 

The  Arteria  superficialis  femoris  arises  nearly  opposite  to 
ihe  profunda,  but  runs  outwards  and  forwards  between  the  long 
adductor  and  the  common  convergence  of  the  psoas  magnus  and 
iliacus  towards  their  insertion  ;  giving  twigs  to  them,  it  passes 
between  the  vastus  internus  and  rectus  femoris,  supplying  the 
crural  triceps  from  the  inside  (compare  the  iliaco-femoral  artery). 

The  Small  muscular  arteries  include  a  series  of  small  in- 
nominate branches  supplying  the  neighbouring  muscles,  and  given 
off  at  intervals  from  the  femoral;  one  of  them  sends  a  long 
branch  to  the  stifle  joint,  and  one  becomes  the  nutrient  artery  of 
the  femur. 

The  Saphenic  artery,  a  small  vessel  in  the  horse,  arises  from 
about  the  middle  of  the  femoral,  and  gains  the  subcutaneous 
region  inside  the  thigh,  generally  passing  between  the  adductors 
brevis  and  longus.  Associated  with  the  saphenic  vein  and  its 
radicals  it  divides  into  an  anterior  and  posterior  branch,  the 
latter  descending  and  forming  just  above  the  tarsus  a  peculiar 
anastomotic  arch  with  the  posterior  tibial,  and  femoro-popliteal 
.arteries 

popliteal  artery. 

(Fig.  159.  at  e.) 

The  popliteal  artery  is  a  continuation  of  the  femoral,  commenc- 
ing between  the  heads  of  the  gastrocnemius  muscle;  it  passes 
under  the  popliteus  muscle,  and  at  the  upper  part  of  the  tibia 
bifurcates  into  anterior  and  posterior  tibial  arteries.  Its  branches 
are  femoro-popliteal,  articular  and  muscular. 

The  Femoro-popliteal  artery,  given  off  just  at  the  origin  of 
the  popliteal,  springs  from  its  posterior  aspect,  and  passes  back- . 


POSTERIOR    TIBIAL    ARTERY. 


il5 


■wards,  between  the  biceps  rotator  and  adductor  magnus,  supplying 
them,  and  gaining  the  subcutaneous  or  posterior  aspect  of  the- 
haunch ;  it  terminates  in  ascending  and  descending  branches,  which 
inosculate  with  the  profunda,  ischiatic,  and  posterior  tibial,  supply- 
ing also  the  skin  at  the  back  of  the  haunch.  The  oMicular 
branches  assist  in  supplying  the  stifle  joint ;  the  muscular  go  to 
the  gastrocnemius ;  one  slender 
twig  descends  iu  front  of  the 
flexor  perforatus,  along  with  the 
popliteal  nerve,  and  anastomoses 
with  a  recurrent  branch  of  the 
posterior  tibial  artery  near  the 
tendo-Achillis. 

The  Posterior  tibial  artery  lies 
beneath  the  popliteus,  flexor  perfor- 
ans,  and  accessorius  muscles,  becom- 
ing more  superficial,  and  covered  by 
the  tibial  fascia,  as  it  travels  down 
the  side  of  the  leg  to  the  crest  of 
the  OS  calcis,  where  it  terminates 
in  the  tarsal  arch,  whence  spring 
usually  two  recurrent  branches, 
which  inosculate  with  small  branches 
of  the  popliteal  and  the  saphenic 
arteries.  Small  branches  are  given 
off  by  it  to  supply  the  muscles,  the 
tarsal  joint,  and  the  nutrient  artery 
of  the  tibia. 

From  the  S  shaped  arch  formed 
at  the  hock  by  the  above  anasto- 
moses, two  small  branches  arise, 
the  internal  and  external  jplantar 
arteries.  Each  clings  to  its  relative 
side  of  the  deep  flexor  tendon,  and 
at  the  level  of  the  upper  end  of  the 
suspensory  ligament,  both  anasto- 
mose with  the  perforating  pedal 
artery,  forming  a  second  or  inferior  anastomotic  arch.  From  this 
arch  are  given  off  two  small  vessels  which  ramify  over  the  flexor 
tendons,  and  au  external  and  internal  interosseov.3  'plantar 
artery ;    the  latter  is  the  larger,  and  appears  to  be  the  continua- 


FlG.  160. 
Arteries  of  the  right  posterior  limb- 
external  view.  1,  Popliteal ;  2  2,  Poste- 
rior tibial;  3  3,  Anterior  tibial, o,  Per- 
oneal ;  h.  Muscular  branches ;  4,  Perfor- 
ating pedal ;  5,  Great  metatarsal. 


416  ANGIOLOGf, 

tion  of  the  perforating  artery,  running  down  the  inner  border  of 
the  suspensory  ligament ;  the  external  one,  very  small,  passes 
down  the  outer  border.  At  the  fetlock  joint  these  vessels 
unite  with  the  great  metatarsal  artery  to  form  the  sesamoidean 
arch. 


ANTERIOR    TIBIAL    ARTERY. 
(Fig.  160.  3,  3.) 

This  is  part  of  the  main  trunk,  being  really  the  continuation 
of  the  popliteal ;  it  winds  forwards  between  the  tibia  and  fibula 
to  the  fore  part  of  the  leg,  gaining  it  midway  between  the  stifle 
and  hock.  It  lies  between  the  deep  face  of  the  flexor  metatarsi 
muscle  and  the  tibia.  At  the  hock  it  passes  obliquely  outwards, 
crossing  the  joint,  and  becomes  the,  great  metatarsal  artery  at 
the  proximal  end  of  the  metatarsus.  It  gives  off  twigs  to  the 
adjacent  muscles,  which  anastomose  with  the  popliteal,  and  the 
peroneal  branch,  which  supplies  and  runs  under  the  peroneus, 
and  it  finally  divides  about  the  tarsus  into  the  great  ^metatarsal 
and  perforating  pedal  arteries. 

The  Arteria  pedis  perforans,  or  Perforating  pedal  artery 
passes  through  the  tarsal  joint,  in  a  canal  between  the  cuboid 
and  cuneiformes  magnum  and  medium,  down  the  back  of  the 
metatarsus,  to  the  arterial  arch  formed  by  the  plantar  branches 
of  the  posterior  tibial  artery. 


GREAT  METATARSAL  ARTERY. 
(Fig.  160.  5.) 

The  great  metatarsal  artery  originates  at  the  proximal  and 
external  aspect  of  the  large  metatarsal  bono  ;  lying  in  the  groove 
between  it  and  the  small  metatarsal  bone,  it  insinuates  itself 
between  them,  passing  under  the  osseous  nodule  of  the  latter-, 
it  gains  the  back  of  the  large  bone,  passing  through  the  bifurca- 
tion of  the  suspensory  ligament,  and  finally  anastomoses  with 
the  internal  and  sometimes  the  external  interosseous  plantar 
branches  of  the  posterior  tibial ;  thus  forming  the  sesamoidean 
arch,  whence  spring  the  external  and  internal  digital  arteries, 
which  gain  the  sides  of  the  fetlock. 


DIGITAL    ARTERIES.  4?'^ 

DIGITAL    ARTERIES. 

The  digital  arteries,  which  are  alike  in  the  fore  and  hind 
limbs,  originate  at  an  acute  angle  below  the  bifurcation  of  the 
suspensory  ligament,  in  front  of  the  flexor  tendons,  passing  over 
the  inner  and  outer  sides  of  the  fetlock  joint,  accompanied  by 
satellite  veins  and  nerves  ;  the  artery  being  central,  and  the 
nerve  posterior.  Each  runs  down  the  side  of  the  digit,  inside 
the  lateral  cartilage,  to  the  superior  border  of  the  ala  of  the  os 
pedis,  thence  they  reach  the  tendinous  surface  of  the  bone, 
terminating  at  the  plantar  foramina  on  either  side  of  the 
insertion  of  the  flexor  pedis  perforans.  They  supply  numerous 
twigs  to  the  flexor  and  extensor  tendons,  fetlock  pad  and  joint, 
and  give  off  the  following  branches,  which  are  usually  regarded 
as  the  arteries  of  the  foot — 

Perpendicular.  I  Artery  of  the  Frog. 

Transverse.  I  Preplantar  ungual. 

Plantar  ungual. 

The  Perpendicular  artery,  which  arises  at  right  angles,  below 
the  middle  of  the  os  suffraginis,  descends  on  the  side  of  the  digit, 
inclining  forwards,  and  terminates  above  the  coronary  ligament  by 
anastomosing  with  its  fellow,  their  union  forming  the  superficial 
coronary  arch,  whence  spring  about  twenty  branchlets,  which 
descend  to  the  coronary  substance. 

The  Transverse  artery,  given  off  under  the  lateral  cartilage, 
passes  forward  between  the  .front  of  the  bone  and  the  extensor 
tendon,  and  inosculates  with  its  fellow,  forming  a  second  arch — 
the  deep  coronary  arch  (superior  coronary  circle),  from  which 
spring  several  branches  to  the  neighbouring  parts,  some  passing 
on  to  the  superficial  c  ironary  arch ;  a  second  branch  inosculates 
with  its  fellow  posteriorly  just  above  the  navicular  bone. 

The  Artery  of  the  Frog  arises  behind  the  pastern  joint  at 
the  superior  part  of  the  lateral  cartilage,  entering  the  sensitive 
frog.  It  divides  into  anterior  and  posterior ;  the  latter  also 
assists  in  supplying  the  lateral  cartilage. 

The  Preplantar  ungual,  or  Lateral  laminal,  given  off  at 
the  posterior  aspect  of  the  ala  of  the  distal  phalanx,  passes 
through  the  notch  and  foramen  between  the  retrossal  and  basilar 
processes,  and  along  the  preplantar  groove  in  the  wall  of  the 
bone,  at  the  anterior  extremity  of  which  it  terminates  by  several 
branches,  which   enter  the  pedal  bone,  and  anastomose  with  the 

2  e 


428  ANGIOLOGY. 

circiilus  arteriosus.  At  its  origin,  a  retrograde  branch  passes  to- 
the  bulb  of  the  frog  ;  and  after  traversing  the  preplanter  groove, 
it  gives  off  a  second  retrograde,  which  supplies  the  external  part  of 
the  lateral  cartilage,  one  twig  inosculating  below  with  the  circumflex 
artery.  It  supplies  numerous  ascending  and  descending  branches 
which  ramify  in  the  sensitive  lamina,  anastomosing  with  those 
of  the  coronary  arch  and  circumflex  artery. 

The  Plantar  ungual  is  the  terminal  branch  of  the  digital ; 
it  passes  through  the  plantar  foramen  on  the  tendinous  surface 
of  the  OS  pedis,  and  enters  the  bone,  within  which  it  inosculates 
with  its  fellow,  forming  the  circulus  arteriosus,  or  plantar  circle, 
from  which  spring  ascending  and  descending  branches.  The 
former  are  the  anterior  laminals,  which  leave  the  bone  through 
numerous  apertures  on  its  wall,  and  ramify  among  the  sensitive 
laminae  ;  the  latter  are  the  inferior  communicating  arteries, 
which  average  fourteen  in  number ;  they  pass  through  the 
foramina  situated  just  above  the  edge  of  the  os  pedis,  and 
unite  outside  to  form  the  circumflex  artery,  which  rims  round 
the  toe,  giving  off  ascending  branches  to  the  sensitive  laminae, 
and  about  fourteen  descending  ones,  the  solar  arteries,  which 
supply  the  sensitive  sole,  uniting  posteriorly  to  constitute 
the  inferior  circumflex  artery. 

Anterior  Aorta. 

(Fig.  154.  e'.) 
The  anterior  aorta  is  rather  more  than  one  inch  in  length,  ami 
passes  obliquely  upwards  and  forwards,  between  the  layers  of  the 
anterior  mediastinum,  over  the  right  auricle,  under  the  trachea, 
and  to  the  left  of  the  anterior  vena  cava  ;  after  furnishing  a  few 
insignificant  twigs  to  the  pericardium  and  mediastinum,  it  divides 
into  the  right  and  left  arteria  innominata,  or  brachial  arteries. 


BRACHIAL    ARTERIES. 
(Fig.  154.  i,  k.) 

The  brachial  arteries  separate  at  an  acute  angle,  the  left  being 
uppermost,  and  pursue  a  diverging  course  towards  the  anterior 
aperture  of  the  thorax,  whence  they  proceed  to  the  pectoral  limbs> 
winding  round  the  first  ribs,  and  below  the  scalenus  muscles;  the 
right  one  gives  off  the  common  carotid  trunk  ;  hence  it  is 
distinctively  known  as  the  brachio-cephalic  artery,  and  is  larger 


BRACHIAL    ARTERIES. 


419 


than  the  left.  Both  pass  forward  between  the  layers  of  the 
anterior  mediastinum,  the  right  below,  the  left  to  the  side  of  the 
trachea,  and  partly  under  the  oesophagus. 

The  following  are  the  arteries  given  off  alike  by  both  brachials. 
The  first  four  arise  within  the  thorax,  the  next  two  at  its  entrance, 
while  the  last  two  arise  externally. 


Dorsal. 

Superior  cervical. 
Vertebral. 
Internal  thoracic. 


External  thoracic. 
Inferior  cervical. 
Prescapular. 
Subscapular. 


Fia.  161. 


Arteries  of  the  neck  exposed  on  the  left  side,  o,  Anterior  aorta;  a'.  Left  brachial;  a",  Eight 
"  brachial,  or  brachio-cephalic  ;  6,  Left  dorsal ;  c  c,  Superior  cervical ;  d,  Vetebral ;  e.  Inferior 
cervical ;  /,  Cephalic  or  common  carotid  ;  /',  Left,  and  /",  Eight  carotid  ;  g  g,  (Esophageal  twigs  ; 
h  h.  Tracheal  twigs ;  i  i,  Muscular  twigs ;  /;,  Thyroid  ;  I,  Thyro-laryngeal ;  m,  Branch  to  Parotid 
gland. 


The  Dorsal  artery  runs  on  the  outer  side  of  the  trachea, 
oesophagus,  sympathetic  nerve,  and  longus  colli  muscle,  through 
the  second  intercostal  space,  reaching  the  withers  ;  it  supplies 
the  muscles  of  that  region.  The  anterior  bran-ch  goes  to  the 
splenius  and  complexus  major,  anastomosing  with  the  terminal 
twigs  of  the  cervical.  Within  the  thorax,  the  dorsal  gives  off  a 
few   twigs    to    the   mediastinum,  and   a   large   subcostal   branch 


420  ANGIOLOGY. 

which  furnishes  usually  from  the  second  to  the  fourth  anterior 
intercostal  arteries. 

The  Superior  cervical  artery  arises  anterior  to  the  dorsal, 
sometimes  along  with  it,  having  the  same  relations  until  it  passes 
through  the  first  intercostal  space.  It  then  runs  upwards  along 
the  ligamentum  nuchse,  covered  by  the  complexus  major,  as  far 
as  the  vertebra  dentata,  distributing  branches  to  the  muscles  of 
the  neck,  and  anastomosing  with  the  dorsal  and  vertebral 
arteries.  Within  the  thorax,  it  gives  otf  the  first  intercostal 
artery,  and  a  twig  to  the  mediastinum. 

The  Vertebral  artery  arises  opposite  the  first  rib,  gains  the 
outer  side  of  the  trachea  and  oesophagus,  and  leaves  the  thorax, 
passing  under  the  transverse  process  of  the  seventh,  and  through 
the  foramina  in  the  transverse  processes  of  the  sixth  to  the 
second  cervical  vertebrae,  covered  by  the  intertransversalis  colli. 
On  reaching  the  atlas  it  anastomoses  with  the  retrograde  branch 
of  the  occipital  artery,  or  ramus  anastomoticus,  which  comes 
through  the  posterior  foramen  on  the  wing  of  the  atlas.  Here 
it  is  covered  by  the  obliquus  capitis  posticus  muscle.  It  supplies 
branches  to  the  muscles  of  the  neck,  also  to  the  spinal  cord  and 
its  membranes,  through  the  intervertebral  foramina. 

The  Internal  thoracic.  Pectoral,  or  Mammary  artery,  ori- 
ginates at  the  first  rib,  opposite  the  vertebral.  It  descends  to  the 
second  bone  of  the  sternum,  passing  over  the  costal  cartilages  to 
the  ensiform,  where  it  splits  into  anterior  abdominal,  and  asternal 
branches,  after  giving  twigs  to  the  pericardium  and  mediastinum ; 
and  intercostal  branches,  which  are  distributed  to  the  pectoral 
muscles,  anastomosing  with  the  external  thoracic  and  first  seven 
intercostal  arteries.  In  the  young  it  supplies  the  thymus  gland. 
The  anterior  abdominal  leaves  the  thorax  at  the  ensiform 
cartilage,  penetrates  the  rectus  abdominis,  and  anastomoses  with 
the  epigastric  artery.  The  asternal  artery  winds  round  the 
cartilages  of  the  false  ribs,  crossing  the  digitations  of  the  trans- 
versalis  abdominis,  and  terminating  in  the  thirteenth  intercostal 
space,  by  anastomosing  Avith  the  intercostal  artery  ;  it  supplies 
the  diaphragm  and  transversalis  muscles. 

The  Inferior  cervical  artery  is  given  off  as  the  brachial 
leaves  the  thorax,  passing  between  the  jugular  confluent  and  the 
pectoralis  parvus,  and  dividing  into  ascending  and  descending 
branches.  The  former  runs  between  the  levator  humeri  and  sub- 
scapulo-hyoideus,   supplying  the  lymphatic  glands   and   adjacent 


BRACHIAL    ARTERIES. 


421 


muscles ;  the  latter  lies  between  the 
pectoralis  anticus  and  levator  humeri, 
terminating  in  the  pectoral  muscles. 

The  External  thoracic  or  mam- 
mary artery  arises  close  to  the  inferior 
cervical,  turns  round  the  anterior 
border  of  the  first  rib,  and  passes 
along  the  internal  aspect  of  the  pec- 
toralis magnus  and  parvus,  a  small 
branch  accompanying  the  spur  vein, 
and  ramifying  in  the  panniculus. 

The  Prescapular  artery  arises 
from  the  brachial,  in  front  of  the 
tendon  of  the  subscapularis,  passing 
between  it  and  the  antea-spinatus ; 
it  is  accompanied  by  a  vein  and 
nerve  to  the  dorsum  scapulae,  supply- 
ing the  shoulder  joint,  pectoralis  parvus, 
scapular  muscles,  and  flexor  brachii 
tendon. 

The  Subscapular  ■  artery  arises  at 
right  angles  from  the  brachial,  just 
before  it  becomes  the  humeral,  near 
the  interstice  separating  the  subscapu- 
laris and  teres  internus  muscles.  It 
passes  up  the  inner  side  of  the  caput 
magnum,  and  terminates  at  the  dorsal 
angle  of  the  scapula,  supplying 
branches  to  the  latissimus  dorsi,  scapu- 
lar, and  lateral  thoracic  muscles  ;  also 
the  nutrient  scapular,  and  the 
scapulo-humeral^  or  posterior  cir- 
cumflex artery,  which  passes  outwards 
behind  the  shoulder  joint,  under  the 
caput  magnum  and  postea-spinatus, 
terminating  in  the  external  muscles 
of  the  region. 

When  the  brachial  artery   reaches 
the  humerus  it  assumes  the  name  of 
the  humeral  artery,  just  as  the  exter 
nal  iliac  becomes  the  femoral -as  it 


Fig.  162. 
Arteries  of  the  anterior  limb— viewed 
from  inside.  1,  Brachial ;  2,  Humeral 
3,  Anterior  radial ;  4,  Posterior  radial; 
5,  Recurrent  radial ;  6,  Eadio-palmar 
7,  Large  metacarpal ;  a,  Prescapular  ; 
b,  Subscapular ;  V,  Branch  to  latissi 
mus  dorsi ;  6",  Posterior  circumflex 
V",  Scapular  nutrient  and  muscular 
branch;  b"",  Main  branch  supplying 
the  muscles ;  c,  Antarior  circumflex  ; 
d,  Humeralis  profunda :  e.  Cubital ; 
e'.  Nutrient  artery  of  humerus;  e", 
Branch  to  inferior  brachial  glands  ; 
6"',  Descending  branch  forming  supe- 
rior carpal  arch ;  e"".  Anterior  sub- 
cutaneous; /,  Intsrosseous ;  /',  Branch 
to  the  carpus ;  g.  Muscular  branches. 


passes  the  pelvic  brim. 


422 


AJfGIOLOGY. 


HUMERAL    ARTERY. 

(Fig.  162.  2.) 

The  humeral  artery,  the  continuation  of  the  brachial,  descends 
obliquely  backwards,  along  the  inner  side  of  the  humerus  ;  just 
above  the  elbow  joint  it  divides  into  anterior  and  posterior  radial 
arteries,  or  more  correctly  speaking  it  gives  off  the  former,  and  is 
continued  by  the  latter.  Its  principal  branches  are  as  follows  : — 
Anterior  circumflex.  I  Cubital. 

Humeralis  profunda.  |  Coraco-radial. 

Anterior  radial. 

The  Prehumeral  or  Anterior  circumflex  artery  passes 
between  the  two  heads  of  the  coraco-humeralis,  reaches  the  front 
'of  the  humerus,  and  terminates  in  the  levator  humeri,  giving 
twigs  to  the  flexor  brachii,  coraco-humeralis,  and  the  shoulder 
joint,  anastomosing  with  the  posterior  circumflex. 

The  Arteria  humeralis  profunda  arises  near  the  conjoined 
tendon  of  the  latissimus  dorsi  and  teres  intemus,  is  divided  into 
two  chief  branches,  which  are  distributed  to  the  caput  magnum 
and  medium,  the  anconeus,  humeralis  obliquus,  and  extensor 
metacarpi  magnus,  anastomosing  by  one  branch  with  the  anterior 
radial  artery. 

The  Cubital  or  Ulnar  artery  passes  backwards  beneath  the 
ficapulo-ulnaris,  along  the  lower  border  of  the  middle  head  of  the 
triceps  extensor,  down  the  forearm,  between  the  external  and 
middle  flexors  of  the  metacarpus,  with  the  cubital  nerve  and  vein, 
inosculating  at  the  knee  with  the  recurrent  branch  of  the  posterior 
radial  artery,  so  forming  the  superior  carpal  arch.  It  gives  off 
branches,  to  the  caput  medium,  scapulo-ulnaris,  pectoralis  trans- 
versus,  brachial  fascia,  and  flexors  of  the  leg ;  also  a  nulrient 
artery  to  the  humerus,  and  twigs  to  the  elbow  joint,  with  a 
small  anterior  subcutaneous  branch 

The  CoRACO-RADiAL  artery,  given  off  nearly  opposite  to  the 
last,  passes  forwards  to  the  flexor  brachii  muscle,  dividing  into 
ascending  and  descending  branches. 

The  Spiral  or  Anterior  radial  artery  is  given  off  at  an 
acute  angle,  just  above  the  condyle  of  the  humerus.  It  descends 
over  the  anterior  surface  of  the  elbow  joint,  and  beneath  the 
flexor  muscles  of  the  fore-arm  and  origin  of  the  extensor  meta- 
carpi, where  it  meets  the  radial  nerve.      They  travel  together  irt 


POSTERIOR    RADIAL   ARTERY  423 

front  of  the  radius,  and  approach  the  knee  below  the  extensor 
pedis.  It  divides  into  numerous  branches,  which  are  distributed 
to  the  capsular  ligament  of  the  carpus  and  extensor  muscles, 
arastomosing  with  the  interosseous  branch  of  the  posterior  radial 
artery. 

POSTERIOR    RADIAL    ARTERY. 
(Fig.  162.  4.) 

The  posterior  radial  is  the  continuation  of  the  humeral  artery. 
It  passes  down  the  inner  side  of  the  fore-arm,  with  a  vein  and 
nerve,  inclining  backwards  beneath  the  flexor  metacarpi  internus, 
and  is  sometimes  described  as  dividing  at  the  distal  end  of  the 
radius  into  large  and  small  metacarpals  ;  it  can  be  felt  just  behind 
the  insertion  of  the  flexor  brachii.  It  supplies  twigs  to  the  elbow 
joint,  which  anastomose  Avith  those  of  the  ulnar,  and  muscular 
branches  to  the  posterior  region  of  the  arm,  with  the  following 
named  branches  : — 

Interosseous.  |  Radio-palmar. 

Recurrent  radial. 

The  Interosseus  artery  of  the  fore-arm  comes  off  near  the 
xadio-ulnar  arch,  through  which  it  passes  outwards,  crossing  the 
posterior  surface  of  the  radius  below  the  perforans.  It  then 
<lescends  in  the  radio-ulnar  groove,  covered  by  the  extensor 
suffraginis,  and  inosculates  with  the  anterior  radial,  forming  a 
plexus  above  the  carpus  ;  it  yields  branches  to  the  elbow  joint 
and  flexor  muscles,  also  the  nutrient  radial,  to  supply  the  radius. 

The  Recurrent  radial  artery  is  a  small  branch  given  off 
just  above  the  carpus ;  passing  outwards  and  downwards,  under 
the  flexor  metacarpi  medius,  it  inosculates  with  the  cubital  and 
forms  the  superior  carpal  arch,  from  which  a  branch  descends  in 
the  thickness  of  the  annular  ligament,  to  inosculate  with  the 
radio-palmar,  below  the  carpus,  and  form  the  inferior  carpal 
arch. 

The  Radio-palmar  or  Small  metacarpal  artery  is  given  off 
at  an  acute  angle.  It  passes  the  inner  and  posterior  aspect  of 
the  carpus,  external  to  the  posterior  annular  ligament,  which 
separates  it  from  the  large  artery.  About  the  head  of  the  meta- 
carpus it  crosses  from  the  inner  to  the  outer  side  at  the  back  of 
the  leg;  inosculating  with  a  descending  branch  from  the  superior 
■carpal  arch,  and   so  forming  the  inferior  carpal  arch,  whence 


424  ANGIOLOGY. 

originate  two  anterior  and  two  posterior  interosseous  palraars. 
The  anterior  ones  pass  round  the  heads  of  the  small  metacarpal 
bones,  and  along  the  grooves  between  them  and  the  large  bone, 
anastomosing  with  the  spiral  above,  and  a  branch  of  the  large 
metacarpal  artery  below.  The  posterior  interossei  descend  on 
either  side  of  the  suspensory  ligament,  inosculating  near  the 
distal  end  of  the  metacarpus  with  branches  from  the  large  meta- 
carpal artery.  One  of  them  gives  off  the  nutrient  artery  of  the 
great  metacarpal  bone. 

LARGE  METACARPAL  ARTERY. 
(Fig.  162.  7.) 

This  is  the  continuation  of  the  posterior  radial  artery.  It 
runs  beneath  the  posterior  annular  ligament  in  company  with  the 
flexor  tendons,  afterwards  descending  to  their  inner  side,  along 
with  the  internal  metacarpal  nerve  and  vein.  Above  the  fetlock 
it  passes  between  the  tendons  and  suspensory  ligament,  dividing 
into  the  external  and  internal  digital  arteries.  At  its  bifurca- 
tion it  gives  off  a  recurrent  branch,  which  divides  and  ascends, 
one  branch  on  the  inner,  another  on  the  outer  lateral  aspect  of 
the  suspensory  ligament,  anastomosing  with  the  posterior  inter- 
ossei. From  the  sesamoidean  arch,  thus  formed  by  union  of  all 
the  posterior  arteries  of  the  region,  the  digital  arteries  may  be 
said  to  arise,  and  likewise  small  transverse  branches,  which 
encircle  the  fetlock  joint.  The  metacarpal  artery  gives  off 
branchlets  to  the  tendons  and  ligaments  during  its  course. 

The  circulation  of  the  digit  is  the  same  as  in  the  pelvic  limb. 

Cephalic  and  Carotid  Arteries. 

(Fig.  161.//'/".) 

The  right  brachial  artery,  besides  supplying  branches  corre- 
sponding to  those  of  the  left,  gives  off  the  common  carotid  or 
cephalic  artery,  which  is  detached  at  an  acute  angle,  and  directed 
forwards  under  the  trachea  and  above  the  anterior  vena  cava. 
On  reaching  the  anterior  opening  of  the  thorax,  it  bifurcates, 
forming  the  Left  and  Right  carotids,  which  pass  up  the  side  of 
the  neck,  diverging  as  they  ascend,  at  first  below,  afterwards  on 
the  sides  of  the  trachea,  to  which  they  are  attached  by  areolar 
tissue.      At  the   middle  of  the    neck,   they  reach    the    posterior 


OCCIPITAL    ARTERY.  425 

tracheal  aspect,  and  are  continued  to  the  level  of  the  larynx, 
where  they  break  up.  Throughout  their  course,  they  are  accom- 
■  panied  by  the  par  vagum,  cervical  portion  of  the  sympathetic, 
and  inferiorly  by  the  recurrent  nerves,  all  being  enclosed  in  the 
same  sheath.  The  arteries  are  covered  at  the  lower  part  of  the 
neck  by  the  scalenus  and  levator  humeri;  in  the  middle  by  the  sub- 
scapulo-hyoideus,  which  separates  them  from  the  jugular  vein  ;  and 
they  are  related  with  the  rectus  capitus  anticus  major,  and  longus 
colli  superiorly.  The  carotid  and  jugular  are  usually  separated 
by  slips  of  the  subscapulo-hyoideus,  but  at  the  entrance  of  the 
thorax  they  contact,  the  artery  lying  superiorly.  The  carotids 
give  off  several  small  branches  to  the  muscles  of  the  neck,  twigs 
to  the  trachea  and  oesophagus,  and  near  their  termination,  the 
thyroid  and  thyro-laryngeal  arteries.  The  thyroid  artery  enters 
the  inferior  part  of  the  thyroid  gland,  to  which  it  is  distributed. 
The  thyro-laryngeal  arises  just  above  the  latter,  opposite  the 
upper  tracheal  ring,  winds  round  the  trachea,  and  divides  into 
branches,  supplying  the  thyroid  body,  pharynx,  and  larynx. 

The   carotid  artery  terminates  by  a  trifurcation,   forming  the 
following  important  arteries  : — 

Occipital.  I  Internal  carotid. 

External  carotid. 


OCCIPITAL    ARTERY. 

(Fig.  163.  1.) 

The  occipital  artery  comes  ofif  at  the  carotid  trifurcation.  At 
first  it  accompanies  the  internal  carotid,  then  crosses  it,  and 
reaches  the  under" -fliirface  of  the  wing  of  the  atlas,  at  the  back  of 
the  guttural  pouch,  passing  between  the  submaxillary  gland  and 
anterior  straight  muscles  of  the  head,  through  the  external  anterior 
foramen  of  the  atlas,  and  at  the  upper  surface  of  the  latter  it 
divides  into  the  cerebrospinal  and  musculo-occipital.  It  is 
crossed  by  the  par  vagum  and  spinal  accessory  nerves  and  the 
cervical  portion  of  the  sympathetic  chain,  and  accompanied  by 
divisions  of  the  inferior  branch  of  the  spinal  nerves.  Its  branches 
Rre  these  : — 

Prevertebral.  I  Ramus  anastomoticus. 

Mastoid.  |  Musculo-occipital. 

Cerebro-spinal. 


426  ANGIOLOGY. 

The  Prevertebral  artery  comes  off  as  it  crosses  the  internal 
carotid,  and  divides  into  muscular  and  meningeal  branches,  the 
muscular  going  to  the  anterior  straight  muscles  of  the  head  and 
occipito-atloidean  articulation.  The  meningeal  are  small  superior 
and  inferior  branches,  which  are  distributed  to  the  dura  mater 
through  the  foramen  lacerum  basis  cranii,and  the  condyloid  foramen. 

The  Mastoid  artery  leaves  the  trunk  opposite  the  pre- 
vertebral, is  directed  to  the  mastoid  foramen  of  the  temporal 
bone,  passing  over  the  styloid  process  of  the  occipital,  under  the 
obliquus  capitis  anticus.  It  gains  the  parieto-temporal  conduit, 
and  inosculates  with  the  meningeal  branch  of  the  internal  maxillary 
artery.      It  supplies  the  'temporal  muscle,  and  the  dura  mater. 

The  Eamus  Anastomotic  us'""  is  detached  at  the  under  surface 
of  the  wing  of  the  atlas ;  it  passes  backwards  through  the  posterior 
foramen  under  the  obliquus  capitis  posticus,  and  inosculates 
with  the  vertebral  artery.  It  supplies  numerous  muscular  twigs, 
and  furnishes  a  direct  communication  between  the  carotid  and 
vertebral  arteries. 

The  MUSCULO-OCCIPITAL  artery  arises  from  the  occipital,  in  the 
alar  gutter;  covered  by  the  obliquus  capitis  posticus,  it  passes 
transversely  outwards  to  the  posterior  straight  muscles,  and 
divides  into  ascending  muscular  and  cuticular  branches  for  the 
occipital  region,  and  descending,  which  anastomose  with  the 
superior  cervical  artery. 

The  Cerebro-spinal  artery  springs  from  the  occipital  in  the 
alar  gutter,  and  enters  the  neural  canal  through  the  internal 
atloid  foramen,  traverses  the  spinal  dura  mater,  dividing  on  the 
inferior  surface  of  the  cord  into  an  anterior  branch,  which 
passes  forwards,  anastomosing  by  convergence  with  its  fellow 
from  the  opposite  side,  to  form  the  basilar  trunk;  and  a 
2)osterior  branch,  which,  after  a  short  backward  course,  likewise 
anastomoses  with  its  fellow  from  the  opposite  side,  constituting 
the  middle  spincd  artery. 

internal  carotid  artery. 

(Fig.  163.  2.) 

This,  the  second  terminal  of  the  common  carotid,  is  directed 
upwards  towards  the  base  of  the  skull,  to  the  outer  side  of  the 

*  [This  artery  is  described  as  inconstaut  and  variable  ;  doubtless  it  is  the 
latter,  but  hitherto  I  do  not  recollect  ever  to  have  sought  for  it  in  vain. — Ed.] 


EXTERNAL  CAROTID  ARTERY.  427 

■anterior  straight  muscles,  accompanied  in  the  first  part  of  its 
course  by  the  occipital  artery,  the  carotid  being  more  posterior. 
At  the  origin  of  the  prevertebral  and  mastoid  branches,  it  is  in- 
flected forwards,  crossing  the  occipital  behind  the  cornu  of  the  os 
hyoides ;  it  passes  to  the  foramen  lacerum  basis  cranii,  at  first 
lying  in  a  fold  of  the  guttural  pouch,  along  with  the  superior 
cervical  ganglion  and  a  branch  of  the  sympathetic  which  enters 
the  cranium ;  it  is  crossed  by  the  nerves  which  form  the  guttural 
plexus.  Passing  through  the  foramen  lacerum,  it  enters  the 
cranial  cavity  to  assist  in  supplying  the  brain.  For  description 
of  the  cranial  portion  of  this  artery,  see  the  description  of  the 
brain  itself 

EXTERNAL  CAROTID  ARTERY. 
(Fic.  163.  3.) 

The  external  carotid  artery  is  the  continuation  of  the  carotid 
itself,  being  deeply  buried  between  the  guttural  pouch  and 
parotid  gland.  It  passes  forwards  and  upwards,  until  it  reaches 
the  cornu  of  the  os  hyoides,  passing  between  it  and  the  hyoideus 
magnus,  and  curves  upwards  towards  the  neck  of  the  condyle  of 
the  lower  jaw,  where  it  divides  into  superficial  temporal  and 
internal  maxillary  arteries,  the  latter  being  its  continuation. 
In  the  first  part  of  its  course  it  has  the  guttural  pouch,  glosso- 
pharyngeal, and  superior  laryngeal  nerves  on  its  inner,  and  the 
superior  belly  of  the  digastricus  and  the  hypo-glossal  nerve  on 
its  outer  aspect.      From  it  spring  the  four  following  branches  : — 

Glosso-facial.  I  Posterior  auricular. 

Maxillo-muscular.  |  Superficial  temporal. 

The  Glosso-facial  or  Submaxillary  artery  arises  before  the 
carotid  passes  between  the  hyoid  cornu  and  the  hyoideus  magnus. 
It  passes  the  anterior  extremity  of  the  submaxillary  gland,  runs 
along  the  upper  border  of  the  digastricus,  crosses  the  outside  of 
Wharton's  canal,  reaches  the  ramus  of  the  lower  jaw  within  the 
maxillary  space,  and  winds  round  it  subcutaneously,  reaching  the 
cheek,  where  it  ascends  in  front  of  the  masseter  muscle,  and  at  the 
maxillary  spine  terminates  in  ascending  and  descending  branches  ; 
the  latter,  or  lateral  nasal,  passes  forwards;  the  former  divides 
into  dorsal  nasal,  which  goes  inwards,  and  angular  artery  of  the 
eye,  which  passes  backwards  to  supply  the  orbicularis  palpebrarum, 
inosculating  with  branches  from  the  superior  dental  artery.      In 


428  ANGIOLOGY. 

addition  to  twigs  supplied  to  the  submaxillary  gland  and  facial 
muscles,  five  branches  are  given  ofif,  the  pharyngeal,  lingual,  sub- 
lingual, and  inferior  and  superior  labial  or  coronary  arteries. 

The  pharyngeal,  or  ascending  pharyngeal,  is  given  ofif  near 
the  origin  of  the  glosso-facial,  passing  obliquely  upwards  between 
the  comu  of  the  os  hyoides  and  the  hyo-pharyngeal  muscle.  It 
takes  a  flexuous  course  towards  the  pterygoid  process,  terminating 
in  the  velum  palati,  and  giving  off  ascending  and  descending 
branches  to  the  walls  of  the  pharynx. 


Fia.  163. 
Arteries  of  the  head— the  left  maxillary  ramus  being  remolded.  1,  Occipital ;  2,  Internal  carotid ; 
.3.  External  carotid  ;  a,  Branch  to  submaxillary  gland  ;  6,  Prevertebral ;  c,  Mastoid  ;  d  c',  Muscu- 
lar twigs  ;  d,  Ramus  anastomoticus  ;  e,  Occipital  gaining  alar  guttsT  ;  /,  Branch  to  submaxillary 
gland  ;  g  g,  Laryngeal  branches  ;  A,  Giosso-facial ;  h,  Pharyrgeal ;  i  i.  Lingual ;  Tc,  Branch  to  sub- 
maxillary  gland ;  I  I,  Sublingual ;  m.  Branch  to  lymphatic  gland ;  B,  Continuation  of  external 
carotid— it  becomes  the  internal  maxillary  at  the  bend  ;  n,  Spheno-spinal ;  o  o,  Deep  temporals  ; 
p,  Ophthalmic ;  q.  Buccal ;  r.  Orbital  branch  of  dental ;  a,  Dental ;  t,  Spheao-palatine  ;  u.  Palatine  : 
V,  Staphyline. 

The  lingual,  almost  as  large  as  the-  parent  artery,  originates 
near  the  comu  of  the  hyoid  bone,  passes  under  the  hyo-glossus 
brevis  in  company  with  the  glosso-pharyngeal  nerve,  crosses  the 
comiculum,  and  is  thence, prolonged  almost  to  the  free  extremity 
of  the  tongue  in  a  very  tortuous  manner.  This  artery,  sometimes 
called  the  ranine,  is  buried  in  the  interstices  between  the  hyo- 
glossal and  genio-hyo-glossal  muscles  in  company  with  branches 
of  the  lingual  and  hypo-glossal  nerves. 

The  sublingual  artery  is  given  off  at  the  anterior  extremity  of 
tte  submaxillary  gland,  passing  to  the  external  surface  of  the 
mylo-hyoideus,  on  which  it  runs  forwards,  and  along  the  inferior 
surface  of  the  sublingual  gland,  supplying  it  as  well  as  the  genio^ 


EXTERNAL  caKOTID  ARTERY.  429 

"hyo-glossus  and  genio-hyoideus  muscles ;  it  is  then  continued 
along  the  side  of  the  fraenum,  where  it  breaks  up,  its  branches 
being  chiefly  distributed  to  the  mucous  membrane.  The  sub- 
lingual gland  may  be  supplied  by  the  submental  branch  of  the 
lingual. 

The  inferior  lihial  or  coronary  artery  is  the  first  branch 
given  off  after  the  glosso-facial  rounds  the  jaw ;  arising  near  and 
passing  under  the  depressor  labii  inferioris,  it  goes  to  the  under 


Fig.  164. 
Facial  arteries  of  the  left  side,  a,  Maxillo-muscnlar  :  a',  Posterior  masseter  ;  h,  c.  Posterior  auri- 
cular :  d,  Anterior  branch  of  it :  e,  Inferior  aurictilar  branch  ;  /,  Superficial  temporal ;  g,  Sub- 
zygomatic ;  g',  Transverse  facial ;  g",  Masseter ;  h,  Anterior  auricular ;  i  i,  Facial  portion  of 
glosso-facial ;  k  k,  Inferior  coronary ;  I,  Superior  coronary  ;  ;»,  Lateral  nasal ;  n,  Dorsal  nasal ; 
o,  Angular  artery  of  the  eye. 

lip,  supplying  the  buccinator,  depressor  labii  inferioris,  the  glands, 
the  cuticle,  and  buccal  membrane,  anastomosing  with  its  fellow  of 
the  opposite  side. 

The  superior  labial  or  coronary  artery  is  larger  than  the 
inferior.  It  springs  from  the  trunk,  near  the  infraorbital  branch 
of  the  superior  maxillary  nerve,  passes  under  the  dilatator  naris 
lateralis  and  levator  labii  superioris,  anastomosing  with  the 
palato-labial  branch  of  the  internal  maxillary,  and  supplying 
twigs  to  the  nasal  tissues,  upper  lip,  and  buccinator  muscle. 

The  Maxillo-MUSCULAR  artery  arises  just  above  where  the 
main  trunk  passes  between  the  hyoideus  magnus  and  the  cornu 


430  AKGIOLOGY. 

of  the  hyoid  bone,  passes  down  behind  the  posterior  border  of  the 
jaw,  covered  by  the  parotid  gland,  and  divides  into  superficial 
and  deep  branches  ;  the  latter  is  the  pterygoidean  artery,  which 
passes  into  the  pterygoid  muscles,  after  furnishing  branches  to  the 
neighbouring  organs ;  the  former  is  the  posterior  masseter,  which 
■winds  round  the  posterior  border  of  the  lower  jaw,  about  the  inser- 
tion of  the  steruo-maxillaris.  It  passes  into  the  masseter  muscle, 
-anastomosing  with  the  masseter  branch  of  the  subzygomatic  artery. 

The  Posterior  auricular  artery  springs  from  the  posterior 
aspect  of  the  carotid,  behind  the  maxillo-muscular,  ascends  under 
the  parotid,  to  the  back  of  the  base  of  the  ear,  giving  off 
numerous  ascending  branches  ;  it  passes  up  the  posterior  aspect 
of  the  concha  between  the  cartilage  and  the  skin,  the  terminal 
twigs  anastomosing  with  each  other.  Besides  supplying  the  parotid 
and  retrahentes  muscles,  this  artery  gives  off  a  large  branch, 
which  divides  into  deep  and  superficial.  The  deejj  one,  after  giving 
a  small  twig  to  the  middle  ear,  which  enters  by  the  stylo-mastoid 
foramen,  passes  between  the  external  auditory  meatus  and  the 
mastoid  process  of  the  temporal  bone,  dips  into  the  adipose 
tissue  below  the  ear,  and  supplies  the  deep  conchal  muscles.  The 
superficial  branch  passes  to  the  external  side  of  the  concha, 
gaining  the  interior  of  the  conchal  cartilage,  with  the  middle 
auricular  nerve. 

The  Superficial  temporal  artery  ascends  between  the  parotid 
gland,  guttural  pouch,  and  the  neck  of  the  inferior  maxilla,  divid- 
ing after  a  short  course  into  anterior  auricular  and  subzygomatic 
iDranches.  The  anterior  auricular  passes  upwards  to  the  anterior 
aspect  of  the  root  of  the  ear,  between  the  temporo-maxillary  artic- 
ulation, and  the  upper  part  of  the  parotid  gland.  After  giving 
off  twigs  to  the  temporalis  muscle,  and  to  the  interior  of  the 
concha  and  its  cuticle,  it  is  lost  in  the  attolentes  muscles.  The 
subzygomatic  artery  is  much  larger  than  the  anterior  auricular. 
Passing  under  the  parotid,  it  rounds  the  posterior  border  oi  the 
inferior  maxilla  just  below  its  condyle,  and  then  terminates  by 
two  branches  of  nearly  equal  volume,  the  one  being  superior  and 
superficial,  the  other  inferior  and  deep.  The  former  is  the  trans- 
verse facial,  which  runs  under  the  zygomatic  ridge  of  the  anterior 
border  of  the  masseter,  where  it  is  lost,  anastomosing  with  the 
maxillo-muscular  and  glosso-facial  arteries.  The  latter  is  the 
masseter  artery,  which  plunges  into  the  substance  of  the  masseter 
muscle,  anastomosing  with  the  maxillo-muscular  artery. 


INTERNAL    MAXILLARY    ARTERY.  431 

INTERNAL   MAXILLARY   ARTERY. 

(Fig.  16D.  B.) 

The  continuation  of  the  external  carotid  is  the  internal  maxil- 
lary artery,  which  commTences  at  the  inner  side  of  the  temporo- 
raaxillary  articulation,  just  below  the  condyle,  passes  between  the 
neck  of  the  lower  jaw  and  the  cornu  of  the  os  hyoides,  where  it 
describes  two  successive  curves,  the  first  convex  backwards,  the 
second  convex  forwards.  It  passes  through  the  pterygoid  fora- 
men in  the  sphenoid  bone,  and  gains  the  orbital  hiatus ;  crossing 
the  floor  of  the  orbit,  it  enters  the  maxillary  hiatus,  and  palatine 
conduit,  where  it  takes  the  name  of  the  palatine  artery.  The 
internal  maxillary  gives  off  the  following  branches  before  entering 
the  pterygoid  foramen  : — 

Inferior  dental.  I  Tympanic. 

Pterygoid  fasciculus.  |  Spheno-spinal.  ' 

Posterior -deep  temporal.  i 

The  first  two  of  these  pass  downwards,  the  rest  upwards. 

The  Inferior  dental  artery,  given  off  from  the  middle  of  the 
first  curve  of  the  internal  maxillary,  passes  downwards  and  for- 
wards between  the  internal  and  external  pterygoids,  enters  the 
dental  foramen  on  the  inner  surface  of  the  ramus  of  the  lower 
jaw,  accompanied  by  the  dental  branch  of  the  inferior  maxillary 
division  of  the  fifth  nerve,  passes  forward  in  the  bone,  supplying 
the  molars,  and  dividing  at  the  neck  of  the  jaw  into  two  branches, 
one  supplying  the  tilsh  and  incisors,  the  other  making  its  exit 
through  the  mental  foramen,  to  anastomose  with  the  inferior 
coronary  artery,  and  terminate  in  the  gums  and  lower  lip. 

The  Pterygoid E AN  fasciculus  is  a  bundle  of  small  arteries 
which  arises  from  the  second  curve,  and  is  distributed  chiefly  to 
pterygoid,  the  tensor  and  levator  palati  muscles. 

The  Tympanic  artery  is  a  very  small  branch  which  passes  into 
the  petrosal  bone  at  the  base  of  the  Eustachian  tube,  and  gains 
the  walls  of  the  tympanum. 

The  Spheno-spinal  ot  Great  meningeal  artery  enters  the 
cranial  cavity  by  the  foramen  lacerum  basis  cranii,  passing  under 
the  dura  mater,  to  which  it  supplies  numerous  branches ;  it  gains 
the  parieto-temporal  conduit,  inosculating  with  the  mastoid  branch 
of  the  occipital  artery. 

The  Posterior  deep  temporal  artery  arises  just  as  the  main 


432  ANGIOLOGY. 

artery  enters  the  pterygoid  foramen  ;  it  passes  directly  upwards, 
ramifying  in  the  substance  of  the  temporalis  muscle,  and  anas- 
tomosing with  the  massgter  by  a  small  branch  which  passes 
through  the  sigmoid  notch. 

In  the  pterygoid  foramen  the  internal  maxillary  artery  gives 
off  two  branches  : — 

Anterior  deep  temporal.         |  Ophthalmic. 

The  Anterior  deep  Temporal  artery,  given  off  in  the  ptery- 
goid foramen,  passes  upwards  along  the  anterior  border  of  tho 
temporalis  muscle,  in  which  it  becomes  buried,  supplying,  in 
addition,  the  attolentes  and  the  neighbouring  tissues. 

The  Ophthalmic  artery  is  a  large  branch,  which  leaves  the  in- 
ternal maxillary  in  the  pterygoid  foramen,  near  to  and  sometimes 
with  the  last.  By  the  orbital  hiatus  it  gains  the  lower  part  of 
the  orbital  fossa,  forms  a  circular  loop  upon  itself,  and  then  enters 
the  cranial  cavity  through  the  internal  orbital  foramen,  and  ter- 
minates in  meningeal  and  internal  lateral  nasal  branches.  The 
former,  after  distributing  branches  to  the  dura  mater  and  falx 
cerebri,  anastomoses  at  the  base  of  the  crista  galli,  with  its  fellow 
and  the  anterior  cerebral  artery.  The  internal  lateral  nasal  artery 
passes  through  the  cribriform  plate  of  the  ethmoid  bone,  enters  the 
nasal  chamber,  and  is  distributed  over  the  ethmoidal  volutes  and 
septum  nasi.  The  ophthalmic  gives  off  muscular  branches  to  the 
muscles  of  the  eye ;  the  ciliary  arteries,  which  go  to  the  eye- 
ball, and  are  chiefly  distributed  to  the  choroid  coat,  ciliary  pro- 
cesses and  iris  ;  the  arteria  centralis  retinae,  which  passes  through 
the  axis  of  the  optic  nerve ;  the  supraorbital  artery,  which 
passes  up  the  internal  wall  of  the  orbital  fossa  in  company  with 
the  vein  and  nerve,  and  through  the  supraorbital  foramen,  to 
be  distributed  to  the  skin  of  the  forehead  and  muscles  of  tho 
frontal  region ;  the  lachrymal  artery,  which  runs  between  the 
muscles  and  upper  wall  of  the  fossa,  and  terminates  in  the  lach- 
rymal gland  and  upper  eyelid ;  finally,  cranial  branchlets^  which 
are  distributed  over  the  anterior  lobe  of  the  cerebrum,  anasto- 
mosing with  the  anterior  cerebral  artery. 

The  branches  given  off  by  the  internal  maxillary  artery,  after 
leaving  the  pterygoid  foramen,  are  : — 

Buccal.  I  Superior  dental. 

Staphyline.  |  Spheno-palatine. 


VEINS.  433 

The  Buccal  artery  arises  j  ust  before  the  orbital  hiatus  ;  it 
passes  between  the  inferior  maxilla  and  the  pterygoid  muscles, 
supplying  the  molar  glands,  various  muscular  branches,  and  a 
twig  to  the  fatty  cushion  of  the  orbital  fossa. 

The  Staphyline  artery,  very  small,  accompanies  the  nerve  of 
the  same  uarae  through  the  staphyline  groove  to  the  soft  palate. 

The  Superior  dental  artery,  a  large  branch,  leaving  the  orbit 
through  the  maxillary  hiatus,  enters  the  maxilla,  passing  through 
the  dental  canal,  along  the  tops  of  the  molar  fangs ;  at  the  infra- 
orbital foramen,  it  divides  into  two  branches,  one  passing  through 
the  foramen  to  be  distributed  over  the  cheeks,  anastomosing  v^ith 
the  superior  labial,  the  other  terminating  in  the  tush  and  incisors 
of  the  upper  jaw.  The  dental  gives  off  an  orbital  branch  to 
supply  the  lachrymal  sac,  and  other  occular  structures. 

The  Spheno-PALATINE  artery  is  a  short,  thick  trunk,  which 
passes  through  the  spheno-palatine  foramen,  and  divides  into 
branches  which  are  distributed  over  the  walls  of  the  nasal 
chamber. 

PALATINE    ARTERY. 
(Fig.  163.  «.) 

The  continuation  of  the  internal  maxillary  is  the  palatine 
artery,  which  gains  the  posterior  part  of  the  hard  palate  through 
the  palatine  foramen ;  it  then  runs  in  a  furrow  along  the  side  of 
the  palate,  and  inosculates  with  its  fellow,  forming  an  arch,  from 
which  is  given  off  the  palato-lahial  artery,  which  passes  through 
the  foramen  incisivum  to  assist  in  supplying  the  gum  and  lips. 
The  arterial  arch  passes  under  the  free  extremities  of  two  small 
cartilaginous  processes,  one  on  each  side,  which  are  attached 
posteriorly  to  the  bony  palate. 

Veins. 

Veins  are  vessels  which  return  blood  to  the  cardiac  auricles, 
<s.tid  consist  of  two  sets — the  pulmonary,  which  transmit  arterial 
blood  from  the  lungs  to  the  left  auricle,  and  the  systemic,  which 
convey  venous  blood  from  the  somatic  capillaries  to  the  right 
auricle.  They  are  larger  and  more  numerous  than  the  arteries. 
The  smallest  veins  commence  at  the  capillaries,  and  converge  to 
form  larger  ones,  terminating  in  trunks  which  enter  the  heart. 

2  F 


434  ANGIOLOGY. 

Veins  are  superficial  and  deep.  The  former  lie  immediately 
below  the  skin,  and  are  mostly  unaccompanied  by  arteries  ;  the 
latter  are  situated  deeply,  and  usually  related  with  arteries,  and 
hence  they  are  called  satellite  veins.  Two  veins  sometimes 
accompany  one  central  artery.  Veins  anastomose  more  freely 
than  arteries ;  and  in  the  head  they  form  dilated  pouches  or 
sinuses,  and  plexubes  in  the  palate  and  foot  ;  their  coats  are 
thinner,  but  stronger  than  those  of  arteries,  and  collapse  when 
cut  across  or  emptied.  After  death,  they  are  usually  distended 
with  blood,  their  walla  being  thin,  semi-transparent,  and  elastic, 
generally  consisting  of  three  tunics,  arranged  for  the  most  part 
like  those  of  an  artery. 

The  majority  of  veins  are  provided  with  valves,  somewhat 
similar  to  the  semilunar  ones  at  the  origins  of  the  great  arteries. 
These  are  folds  of  the  lining  membrane,  strengthened  by  fibrous 
tissue,  and  present  an  adherent  and  a  free  semilunar  border  when 
the  valves  are  shut.  "When  distended  they  have  a  concave 
surface  towards  the  heart,  and  a  convex  one  towards  the  origin 
of  the  vein  ;  they  may  consist  of  from  one  to  five,  but  generally 
of  two  flaps,  opposed  to  each  other.  The  walls  of  the  veins 
immediately  above  the  valves  are  pouched  into  sinuses,  which 
produces  a  knot  or  swelling.  Their  use  is  to  favour  the 
course  of  the  blood  and  oppose  its  reflux  from  the  heart.  During 
its  normal  flow,  they  are  placed  against  the  walls,  offering  no 
obstacle  to  the  current.  When  the  current  is  intercepted,  the 
valves  are  pressed  back,  the  lefluent  column  of  blood  gets  between 
the  concave  surfaces  of  the  flaps  and  the  dilated  pouches,  pressing- 
the  former  inwards  until  their  edges,  meeting  in  the  centre, 
arrest  the  retrograde  current.  Valves  are  irregularly  distributed, 
and  are  most  numerous  near  the  convergent  points ;  they  are 
absent  in  the  pulmonary,  cranial,  spinal,  pedal,  and  osseous  veins, 
in  the  foetal  umbilical  vessels,  and  vense  cavse  They  are  only 
rudimentary  in  the  portal,  rare  in  the  azygos,  spermatic,  uterine, 
and  ovarian  veins ;  but  numerous,  large,  and  complete  in  those 
of  the  extremities  Their  coats,  like  the  arterial,  are  supplied 
with  capillary  vasa  vasorum.  Their  nerves,  few  and  only  trace- 
able on  the  larger  vessels,  come  from  the  sympathetic  system. 
Veins  may  originate  from  arteries  without  the  intervention  of 
capillaries,  as  in  the  erectile  tissue  of  the  penis. 


CORONARY  VEINS.  435 


PULMONARY  VEINS. 


The  pulmonary  veins  originate  from  the  capillaries  of  the 
corresponding  arteries,  in  the  walls  of  the  air-cells  and  lesser 
air-tubes.  By  repeated  union  they  become  larger,  ultimately 
converging  to  form  from  four  to  eight  trunks,  but  usually 
four,  at  the  root  of  the  lung,  which  enter  the  left  auricle  at  various 
points.  They  are  destitute  of  valves,  which  permits  easy  reflux 
of  blood.  These  veins  differ  from  others  in  the  kind  of  blood 
which  they  convey,  the  latter  being  arterial  instead  of  venous. 

SYSTEMIC   VEINS. 

The  systemic  veins  commence  in  the  capillaries,  Avhich,  by 
repeated  union,  form,  in  entering  the  right  auricle,  the  cardiac  or 
coronary  sinus,  which  opens  directly  into  the  cavity  of  the  auricle ; 
and  two  large  trunks,  the  anterior  and  posterior  venas  cavae,  which 
terminate  by  two  openings.  There  is  a  set  of  systemic  veins 
which  neither  go  directly  to  the  heart  nor  to  the  larger  trunks ; 
i.e.,  the  veins  of  the  chylo-poietic  viscera,  which  unite  to  form 
the  vena  porta,  terminating  in  the  hepatic  substance. 

CORONARY  VEINS. 

The  cardiac  or  coronary  veins  consist  of  one  vena  cordis  magna 
and  numerous  small  venae  cordis  minimse.  The  great  coronary  is 
formed  by  two  branches :  one  is  lodged  in  the  right  ventricular 
furrow,  being  a  satellite  of  the  descending  branch  of  the  right 
coronary  artery  ;  the  other,  a  satellite  of  the  left  coronary  artery, 
passes  up  the  left  ventricular  furrow  to  the  origin  of  the  pulmonary 
artery,  then  backwards,  turning  round  the  base  of  the  left  ventricle, 
finally  uniting  with  the  right  branch  near  the  termination  of  the 
posterior  cava ;  the  common  trunk,  or  coronary  sinus,  enters 
the  right  auricle,  receiving  various  branchlets  from  the  ventri- 
cles and  auricles  ;  these  have  valves  at  their  termination.  The 
lesser  cardiac  veins  are  numerous,  coming  chiefly  from  the  walls 
of  the  right  side,  penetrating  it  by  the  foramina  Thebesii  in 
the  right  auricle. 

The  bronchial  veins,  which  return  the  venous  blood  from  the 
substance  of  the  lungs,  are  satellites  of,  and  disport  themselves  as 
do  the  bronchial  arteries.  At  the  root  of  the  lungs  they  form 
one  vein,  which  enters  the  great  coronary  just  as  it  terminates 
in  the  sinus,  or  rarely  enters  the  auricle  separately. 


436 


ANGIOLOGY, 


POSTERIOR  VENA  CAVA. 
(Fig.  165.  1.) 

The  posterior  vena  cava  returns  the  blood  from  the  posterior 
extremities,  abdominal,  and  pelvic  viscera.  It  corresponds  to  the 
posterior  aorta,  and  commences  at  the  entrance  of  the  pelvic  cavity 
by  the  pair  of  common  iliac  veins,  runs  forwards  under  the  bodies 
of  the  lumbar  vertebrae,  in  contact  with  the  psoas  parvus,  having 
the  posterior  aorta  on  its  left.      On  reaching  the  superior  border 


Fio.  165. 
Abdominal  portion  of  the  posterior  cava— the  cavity  opened  on  the  right  side,  and  most  of  the 
viscera  removed.    1,  Posterior  cava ;  a,  Right,  6,  Left  common  iliac  vein  ;  V,  Left  external  iliac  ; 
i",  Left  internal  iliac  :  c.  Right  circumflex  ilii ;  e'  c',  Lumbars  ;  d,  Left  spermatic  ;  e.  Eight  renal ; 
//,  Hepatic  veins  ;  g.  Diaphragmatic  vein. 

of  the  liver,  it  is  inclined  downwards ;  and  thus  leaving  the  sub- 
lumbar  region,  it  occupies  the  anterior  fissure  of  the  liver,  passes 
through  the  foramen  dextrum  of  the  diaphragm,  into  the  thoracic 
cavity,  then  through  the  notch  in  the  right  lung,  covered  by  a 
reflection  of  pleura,  and  finally  enters  the  right  auricle  of  the 
heart  at  its  postero-external  part.  In  the  abdomen,  it  is  related 
with  the  right  kidney  and  pancreas.  It  receives  the  satellite  veins 
of  the  various  arteries  of  the  region  ;  but  those  of  the  chylo-poietic 


PORTAL    VEIN.  437 

■viscera  form  the  portal  vein,  whose  blood  is  conveyed  by  the 
medium  of  the  hepatic-  veins. 

The  Phrenic  or  Diaphragmatic  veins  commence  in  the  fiessny 
portion  of  the  diaphragm,  forming  two  or  three  large  branches, 
which  enter  the  cava  as  it  passes  through  the  foramen  dextrum. 

The  Hepatic  veins  are  numerous,  and  commence  by  intra- 
lobular branchlets  in  the  capillary  terminations  of  the  hepatic 
artsry  and  vena  porta.  These  discharge  into  sublobular  veins, 
which  unite,  passing  upwards  and  forwards,  unaccompanied  by 
arteries.  Leaving  the  gland  in  the  anterior  fissure,  they  enter 
the  cava  by  a  number  of  minute  oblique  openings,  and  usually 
one  or  two  larger  ones. 

PORTAL    vein. 
(Fig.  166.) 

The  portal  vein  commences  in  the  sublumbar  region,  near  the 
anterior  mesenteric  artery,  concealed  by  the  pancreas,  and  is 
formed  by  the  union  of  three  large  branches,  which  return  the 
blood  from,  the  visceral  organs  of  digestion.  It  is  directed  for- 
wards with  an  inclination  to  the  right,  passes  through  the  pan- 
creatic ring  below  the  vena  cava,  reaches  the  posterior  fissure  of 
the  liver,  and,  entering  the  gland,  it  is  distributed  like  an  artery, 
finally  terminating  in  the  hepatic  veins.  The  branches  which  form 
the  portal  vein  are  the  anterior  and  posterior  mesenteric,  and 
gastro-splenic  veins. 

The  anterior  mesenteric  vein  is  large ;  its  divisions  exactly  corre- 
spond to  the  branches  of  the  anterior  mesenteric  artery,  while  tLe 
•posterior  raesenteric  vein  is  made  up  of  branches  corresponding  to 
those  of  the  posterior  mesenteric  artery.  The  gastro-splenic  vein 
is  large,  formed  by  the  union  of  the  left  gastro-epiploic,  splenic, 
and  gastric  satellites  of  the  splenic  artery,  and  the  posterior 
gasiric  vein.  The  portal  thus  formed  receives  the  right  gastro- 
epirjloic  vein,  the  latter  receiving  the  pyloric,  duodenal,  and  pan- 
creatic  veins,  all  satellites  of  the  corresponding  arteries.  The 
anterior  gastric  vein  enters  separately. 

The  Renal  veins  have  vei-y  thin  wails,  and  are  formed  by  the 
union  of  the  veinlets  which  leave  the  hilus  of  the  kidney,  and  a 
branch  from  the  suprarenal  capsule.  The  left  renal  having  to 
cross  the  posterior  aorta,  is  the  longer. 

The  Spermatic  veins  leave  the  testicles  and  enter  the  sper- 


438 


ANGIOLOGT. 


matic  cord.  On  reachiog  the  abdomen  they  communicate  freely^ 
forming  the  spermatic  plexus,  finally  terminating  in  the  cava 
near  the  renal,  by  one  or  two  trunks.  In  the  female  these  veins 
become  the  utero-ovarian,  which  follow  the  exact  course  of  the 
uter;o-ovarian  arteries. 

The  Lumbar  veins  correspond  to  their  satellite  arteries,  and 
result  from  muscular,  spinal,  and  abdominal  parietal  branches. 


Fi«.  166. 
Viscera,  and  veins  of  the  portal  s,vsteni.  1,  Spleen :  2,  Stomach  ;  3  3,  Convolution  of  small  lutes* 
ine  ;  4,  CsBcnin  ;  5,  Great  colon ;  a  6,  Floating  colon  and  rectum  ;  7,  Pancreas ;  8;  Liver ;  a  a. 
Portal  vein  ;  &,  Anterior  mesenteric  vein  ;  V  V,  Veins  of  siaaU  intestine :  h",  Ileo-caecal ;  b'".  Colic 
vein ;  c  c,  Posterior  mesenteric  vein ;  d,  Gastro-splenif ;  <J',  Posterior  gastric  vein ;  d",  Splenio 
vein  ;  d"'.  Its  i?Mtric  branches, 

They  join  the  upper  surface  of  the  vena  cava.    The  anterior  ones 
often  terminate  in  the  vena,  azygos. 


COMMON  ILIAC  vEma 

(Tio,  165.  a,  6.) 
These  are  two  large,  short  vessels,  forme^i  by  the'  union  of  the 
external  and  internal  iliacs,  the  former  collecting  the  blood  fi^ili 


VEINS    OF    THE    FOOT.  4S& 

the  posterior  extremity,  the  latter  from  the  hinder  part  of  the 
trunk.  They  are  lodged  in  the  angles  of  separation  comprised 
l)etween  the  external  and  internal  iliac  arteries,  the  right  one, 
the  shorter,  passing  above  the  external  iliac  artery  to  meet  the 
left  at  the  origin  of  the  posterior  vena  cava.  The  left  one  before 
it  joins  its  fellow  passes  between  the  body  of  the  last  lumbar 
vertebra  and  terminal  extremity  of  the  posterior  aorta. 


EXTERNAL   ILIAC  VEIN. 
(Fig.  165.  b'.) 

In  studying  the  branches  of  the  external  iliac  vein,  it  is  advis- 
.able  to  commence  at  the  foot.  The  venous  plexuses  of  the  foot 
unite  to  form  two  digital  veins,  and  these  are  succeeded  by  three 
^metatarsals,  the  common  origin  of  the  four  veins  of  the  thigh, 
which  are  distinguished  as  subcutaneous  and  deep.  The  deep  are 
■continued  as  the  popliteal  and  femoral,  the  latter  being  con- 
tinued by  the  external  iliac  vein. 

VEINS  OF  THE   FOOT. 

The  veins  of  the  foot  are  very  numerous,  and  arranged  in  a 
fiuperificial  and  interosseous  netvv'ork.  They  are  valveless,  allowing 
the  blood  to  flow  in  either  direction  during  sudden  emergency. 
The  external  or  superficial  plexuses  are  the  solar,  laminal,  and 
<Xfronary. 

The  Solar  plexus  is  remarkable  for  the  equality  of  the  dia- 
meter of  its  veins  throughout  the  extent  of  the  plantar  surface  of 
the  foot,  as  well  as  for  the  paucity  of  anastomoses  of  them  with 
the  deep-seated  veins.  They  chiefly  terminate  in  the  large  cir- 
^wmfiex  vein  which  accompanies  the  artery  of  the  same  name,  and 
Tsceives  also  descending  twigs  from  the  laminal  plexus,  as  it  passes 
back  to  the  wing  of  the  bone,  and  thence  into  the  coronary 
plexus.  The  remaining  branches  of  the  solar  plexus  reach  the 
small  central  vein,  situated  around  the  semilunar  ridge,  on  the 
solar  surface,  and  terminate  also  in  the  coronary  plexus. 

The  Laminal  plexus  rests  on  the  sensitive  wall  of  the  foot. 
The  branches,  uniform  in  the  sensitive  laminae,  gradually  increase 
in  size  as  they  approach  the  coronet,  where  the  majority  terminate 
in  the  coronary  plexus  ;  the  remainder  pass  down  to  the  circum- 
:flex  vein. 


440  ANGIOLOGY. 

The  Coronary  plexus  surrounds  the  os  coronse  and  upper  part 
of  the  OS  pedis.  Extending  backwards  below  the  lateral  cartilages, 
the  plexus  consists  of  an  anterior  or  middle,  and  two  lateral  por- 
tions; The  middle  coronary  lies  in  front  of  the  foot,  and  receiver 
the  anterior  ascending  branches  of  the  laminal  plexus.  The  lateral 
coronary  plexus  consists  of  a  superficial  and  a  deep  portion,  the 
former  situated  upon,  the  latter  under,  the  lateral  cartilage,  and 
formed  by  the  posterior  branches  of  the  laminal,  the  deep  one 
being  joined  by  veins  from  the  coronet,  and  from  the  ligaments 
and  tendons  of  the  region.  The  veins  of  the  frog  extend  over 
the  external  surface  of  the  sensitive  frog,  ascend  the  sides  of  the 
lateral  cartilages,  and  unite  to  form  a  large  vein,  which,  with 
branches  from  the  superficial  and  deep  coronary  plexuses,  runs 
up  the  lateral  aspect  of  the  os  corontE,  all  uniting  near  its  head 
to  form  the  digital  vein. 

The  internal  or  interosseous  veins  of  the  foot  form  a  system 
of  satellites  to  the  circulus  arteriosus  and  its  branches.  They 
pass  out  of  the  bone  through  the  plantar  foramina,  at  each  side 
of  the  tendinous  surface  ;  thence  up  the  inner  side  of  the  lateral 
cartilages,  finally  uniting  with  the  branches  of  the  deep  coronary- 
plexus. 

DIGITAL  VEINS. 

The  digital  veins,  formed  by  the  union  of  the  deep  and 
superficial  coronaries,  and  veins  from  the  frog,  ascend  the  digit 
in  company  with  the  arteries  and  nerves,  and  terminate  a  little 
above  the  fetlock,  by  uniting  to  form  an  arch  between  the  flexor 
tendons  and  suspensory  ligament.  From  this  arch,  the  sesamoi- 
dean,  spring  the  three  metatarsal  veins.  The  digitals  receive 
branches  corresponding  to  the  perpendicular  and  transverse  divi- 
sions of  the  arteries,  as  well  as  twigs  from  surrounding  structures^ 


METATARSAL  VEINS. 

The  metatarsal  veins  are  three  in  number,  internal,  extenial,. 
and  deep,  originating  in  the  sesamoidean  arch.  The  internal  is. 
the  largest,  and  appears  to  be  a  continuation  of  the  internal 
digital.  It  passes  up  the  cannon  bone,  internal  to,  and  a  little 
in  front  of,  the  flexor  tendons,  accompanied  by  the  internal 
metatarsal  nerve.  Nearing  the  hock,  it  crosses  obliquely  to  the 
anterior  surface  of  the  joint,  where  it  communicates  by  a  larj^ 


SUPERFICIAL    VEINS.  441 

transverse  branch  with  the  origin  of  the  anterior  tibial  vein,  and 
then  passes  along  the  inner  surface  of  the  leg,  forming  the 
anterior  root  of  the  internal  saphenic  vein.  The  external 
metatarsal  vein  occupies  a  position  on  the  outer  side  of  the 
flexor  tendons,  analogous  to  that  of  the  internal.  Towards  the 
superior  extremity  of  the  cannon,  it  anastomos'es  with  the  deep 
vein,  then  continues  its  course  upwards,  accompanied  by  the 
plantar  arteries,  gains  the  hollow-  above  the  tarsus,  passing  along 
the  femoro-popliteal  nerve,  and  forms  the  posterior  root  of  the 
internal  sphenic  vein.  The  deep  metatarsal  vein  originates 
below  the  flexor  tendons,  and  passes  up  underneath  the 
suspensory  ligament,  to  the  inner  side  of  the  chief  interosseous 
plantar  artery.  Below  thi  hock,  it  receives  the  large  anastomotic 
branch  from  the  external  "Sin,  passes  through  the  canal  formed 
between  the  cuboid  and  -^neiform  bones,  ficully  forming  the 
principal  branch  of  the  anisrior  tibial  vein. 

Above  the  hock  there  are  four  large  veins — a  deep-seated  pair, 
the  anterior  and  posterior  tibial,  and  a  superficial  pair,  the 
internal  and  external  saphenic  veins. 

DEEP  VEINS. 

The  Anteeior  tiblil  vein  is  a  satellite  of  the  corresponding 
artery.  It  is  frequently  double,  arising  on  the  anterior  surface 
of  the  hock  by  several  branches,  the  chief  one  being  the  deep 
metatarsal  vein.  Accompanying  the  artery,  between  the  tibia 
and  fibula,  it  joins  the  posterior  tibial  to  form  the  popliteal  vein. 

The  Posterior  tibial  vein  commences  in  the  hollow  in  front 
of  and  inside  the  calcaneum,  by  branches  furnished  principally 
by  the  two  saphenic  veins.  It  passes  up  the  leg,  with  the 
posterior  tibial  arterj,.  scici  under  the  popliteus  muscle  unites 
with  the  anterior  tibiail  vein. 


superficial  veins. 

The  superficial  or  subcutaneous  veins  are  tbe  internal  and 
external  saphenics. 

The  Internal  or  Vena  saphena  major  originates  by  two 
large  roots  at  the  icier  part  of  the  hock.  The  anterior  root  is 
i  continuation  of  tKp  internal,  the  posterior  of  the  external 
saetatarsal  veins ;   tnese  conv<ri^e,  and  form  one  large  vessel  on 


442  ANGIOLOGY. 

the  internal  surface  of  the  leg.  It  ascends,  and  terminating  near 
the  groin,  ina,y  either  pass  through  the  interstice  between  the 
gracilis  and  sartcrius  muscles,  entering  the  femoral  vein ;  or  it 
may  end,  near  the  origin  of  the  gracilis,  by  joining  the  external 
pudic  veins. 

The  External  saphena  or  Vena  saphena  minor,  originates 
at  the  front  of  the  os  calcis,  anastomosing  with  the  posterior  root 
of  the  internal  saphenic,  with  which,  above  the  hock  and  in  front 
of  the  calcaneum,  it  forms  a  large  plexus  of  veins.  It  also  anas- 
tomoses with  the  posterior  tibial  vein,  by  a  large  branch  which 
passes  between  the  tibia  and  flexor  pedis  perforans ;  and  it  runs 
along  the  tendon  of  the  gastrocnemius,  in  company  with  a 
nerve,  terminating  near  the  stifle  joint  in  the  popliteal  vein. 

The  Popliteal  vein,  formed  by  the  union  of  the  anterior  and 
posterior  tibials,  is  a  satellite  of  the  popliteal  artery,  and  receives 
branches  corresponding  to  those  given  off  from  the  latter. 
The  principal  one  is  the  femoro-popliteal,  which  enters  with  the 
external  saphenic  vein. 

The  Femoral  vein,  a  satellite  of  the  artery,  is  the  continuation 
of  the  popliteal.  Its  branches  are  similar  to  those  of  the  femoral 
artery,  with  the  addition  of  the  internal  saphenxi,  which  joins 
about  its  middle  third.  The  femoral  terminates  in  the  external 
iliac  vein. 

The  External  iliac  is  thus  the  continuation  of  the  femoral 
vein  ;  and  is  the  larger  of  the  two  branches  which  form  the 
common  iliac.  In  its  course,  this  vein,  which  commences  at  the 
pubis,  receives  no  important  collateral  branches,  excepting  the 
circumflex  vein  of  the  ilium,  a  satellite  of  the  corresponding 
artery. 

internal  iliac  vein. 

(Fig.  165.  6'.) 
The  internal  iliac  vein,  which,   with  the  external,  forms  the 
common  iliac  trunk,  is  very  short,  and  formed  by  the  union  of 
satellites,  corresponding  to  the  branches  given  off  from  the  inter- 
nal iliac  artery. 

anterior  vena  cava. 

(Fig.  167.  1,  1.) 
The  anterior  vena  cava  is  the  venous  trunk,  which  returns  the 
blood  chiefly  from  the  head,  neck,  fore  extremities,  and  part  of 


ANTERIOR    VENA    CAVA. 


443 


the  thorax.  This  large  but  short  vessel  is  situated  at  the  anterior 
part  of  the  thorax,  between  the  layers  of  the  anterior  mediastinum, 
below  the  trachea,  and  to  the  right  of  the  anterior  aorta,  to  which 
it  corresponds.  It  is  formed  between  the  first  pair  of  ribs,  by  the 
union  of  the  two  jugular  and  two  brachial  veins,  receiving  the 
internal  thoracic,  vertebral,  superior  cervical,  dorsal,  and  the  great 
vena  azygos. 

The  Internal  thoracic,  Vertebral,  and  Superior  cervical 
veins,  are  satellites  of,  and  counterparts  in  distribution  to,  their 
corresponding  arteries. 


Fig.  107. 
Thorax  opeaeJ  on  the  right  side  to  show  the  heart  and  veins.  A,  Heart,  with  left  coronary  vein  ; 
1  1,  Anterior  cava  ;  2,  Postericr  cava  ;*  a,  Lsf t  brachial ;  6,  Right  brachial  cut ;  c,  Left  jugular ; 
d,  Internal  thoracic  ;  d',  A  mediastinal  vein  :  e,  Right  vertebral ;  /,  Dorsal  and  superior  cervical 
veins  discliarging  together  ;  /,  Eight  superior  cervical ;  f,  Right  dorsal ;  o,  Vena  azygos  ;  g',  (Eso- 
phageal ;  g",  Bronchial ;  g"'  g'",  Intercostals. 

The  Dorsal  vein  follows  the  same  course  as  the  dorsal  artery, 
receiving  also  several  intercostal  branches,  the  right  one  returning 
the  blood  from  the  second  to  the  fifth  intercostal  spaces  ;  the  left, 
sometimes  called  the  lesser  vena  azygos,  is  prolonged  as  far  back 
as  the  eleventh  or  twelfth  intercostal  space,  receiving  blood  from 
the  intercostal  veins  of  all  the  spaces  it  crosses. 

On  the  right  side  the  vertebral,  superior  cervical,  and  dorsal 
veins  may  reach  the  vena  cava  separately,  whereas  those  on  the 
Jeft  enter  by  a  common  trunk. 


444  ANGIOLOGY. 

The  Vena  azygos  is  a  long  single  branch,  whose  radicles- 
originate  near  the  first  lumbar  vertubra.  It  passes  forwards  on 
the  right  side  of  the  postarior  aorta,  below  the  bodies  of  the 
dorsal  vertebrae,  reaching  the  sixth,  where  it  becomes  inclined 
downwards,  and  terminates  in  the  anterior  vena  cava.  It  receives 
branches  from  the  spinal  and  psoe  muscles,  the  posterior  thirteen 
right,  and  usually  the  posterior  five  or  six  left  intercostal,  and 
also  the  oesophageal  veins. 

_  ,_^  iiRACHlAL    VEIN. 

vFiG-  167.  a,  I.) 

The  brachial  vein,  the  largest  trunk  which  enters  into  the 
formation  of  the  anterior  vena  cava,  receives  the  greater  part  of 
the  blood  from  the  anterior  extremity,  as  well  as  extrinsic 
branches  corresponding  to  those  of  the  artery,  and  the  sub- 
cutaneous thoracic  or  spur  vein. 

The  Pedal  plexuses  and  digital  veins  are  identical  with  those 
of  the  posterior  limb. 

The  Metacaepal  veins  are  the  external,  internal,  and  inter- 
osseous. The  internal  vein,  by  far  the  largest,  passes  up  the 
limb  to  the  side  of  the  flexor  tendons,  in  company  with  the  artery 
and  nerve,  the  vein  being  in  front,  the  artery  in  the  centre  ; 
passing  the  knee  in  compan}'^  with  the  i;^dio-palmar  artery  it  is 
continued  as  the  internal  subcutaneous  vein.  It  forms  a  free 
anastomosis  with  other  metacarpal  veins,  receiving  also  branches 
from  the  joint.  The  external  metacarpal  is  situated  on  the 
external  side  of  the  flexor  tendons,  accompanied  hy  the  corre- 
sponding nerve,  and  it  also  receives  branches  from  the  skin 
and  adjacent  structures.  On  reaching  the  upper  part  of  the 
trapezium,  it  divides  into  numerous  branches,  which  either  anas- 
tomose with  those  of  the  internal,  or  go  to  form  the  posterior  radial 
and  cubital  veins.  The  deep  or  interosseous  vein  is  very  irregular 
and  flexuous,  and  may  be  double  ;  it  passes  up  the  limb  between 
the  posterior  surface  of  the  cannon  bone  and  the  suspensory  liga- 
ment. At  the  head  of  the  metacarpus,  it  splits  up  to  unite  with 
branches  of  the  external  and  internal  veins,  and  sends  one  or  two 
small  branches,  through  the  carpal  sheath,  which  help  to  form 
the  posterior  radial  vein. 

The  Posterior  radial  vein  is  a  continuation  of  the  meta- 
carpals,   terminating  at  the  lower   end   of   the   humerus    in   the 


DEEP    VEINS.  445 

humeral.  The  artery  is  always  accompanied,  and  in  a  great 
measure  enveloped,  by  three  or  four  venous  branches,  that  freely 
anastomose,  and  result  from  the  terminals  of  the  metacarpals. 

The  Anterior  radial  follows  a  course  similar  to  the  anterior 
radial  artery,  receiving  satellite  branches  equivalent  to  those  of 
the  latter. 

The  Ulnar  or  cubital  accompanies  the  ulnar  artery,  receiving 
muscular  and  cutaneous  branches,  terminating  at  the  inferior 
extremity  of  the  humeral.  It  is  sometimes  double  in  the  latter 
part  of  its  course. 

SUPERFICIAL    veins. 

The  superficial  veins  of  the  arm  and  chest  are  the  external  and 
internal  subcutaneoUs,  which  are  slightly  separated  from  the 
skin  and  fascia  of  the  arm  ;  and  the  subcutaneous  thoracic. 

The  Internal  subcutaneous  vein  ascends  the  limb  on  the 
inner  side  of  the  fore-arm,  at  the  superior  extremity  of  which  it 
passes  obliquely  forwards,  and  terminates  by  two  large  branches 
• — the  basilic  and  the  cephalic.  The  basilic  vein  crosses  the 
pectoralis  transversus,  and  terminates  in  the  humeral.  The 
cephalic  vein  passes  over  the  flexor  brachii  to  the  interstice 
between  the  pectoralis  anticus  and  levator  humeri,  emptying  itself 
into  the  jugular  vein. 

The  External  subcutaneous  vein  is  much  smaller  than  the 
internal,  and  ascends  the  leg  on  the  anterior  surface  of  the  fore- 
arm, terminating  at  the  superior  extremity  by  uniting  either  with 
the  interna],  or  more  commonly,  the  cephalic  vein. 

The  Subcutaneous  thoracic  or  Spur  vein  commences  by 
numerous  branches  in  the  flank,  which  unite  in  one  common 
trunk.  Posteriorly  it  lies  near  the  external  surface  of  the  pan- 
niculus,  being  directed  along  the  superior  border  of  the  pectoralis 
magnus  ;  it  then  dips  into  the  caput  muscles,  terminating  in 
the  humeral,  sometimes  in  the  brachial  vein. 


DEEP    VEINS. 


The  Humeral  vein  is  a  satellite  of  the  corresponding  artery, 
and  lies  behind  it,  commencing  above  the  elbow  by  the  union  of 
the  radial  and  articular  branches.  It  terminates  in  the  brachial 
vein. 

The  Brachial  vein  commences  at  the  scapulo-humeral  articula- 


446  ANGIOLOGY. 

tion,  being  the  continuation  of  the  humeral ;  in  company  with 
the  artery,  it  winds  round  the  first  rib,  below  the  lower  insertion 
of  the  scalenus  muscle,  enters  the  thorax,  uniting  with  its  fellow 
and  the  jugular  confluent  to  form  the  anterior  vena  cava. 

JUGULAR    VEIN. 
(Fig.  168.  2,  4.) 

The  jugular  vein,  the  great  vein  of  the  head,  and  satellite  of 
the  carotid,  commences  by  two  branches,  the  superficial  temporal 
and  internal  maxillary,  just  behind  and  below  the  temporo- 
raaxillary  articulation,  its  origin  thus  corresponding  to  the  break- 
ing up  of  the  external  carotid  artery.  Lodged  at  first  in  the 
posterior  part  of  the  parotid  gland,  in  the  neck  it  is  superficially 
placed,  occupying  the  jugular  gutter,  a  canal  formed  by  the 
levator  humeri  and  sterno-maxillaris  muscles ;  it  enters  the 
thorax,  joining  its  fellow,  between  the  first  ribs,  and  under  the 
trachea,  to  form  the  jugular  confluent,  into  which  the  brachial 
veins  discharge,  the  whole  forming  the  anterior  cava.  The  veins 
joining  the  jugular  correspond  for  the  most  part  to  their  respect- 
ive arteries. 

SUPERFICIAL    TEMPORAL    VEIN. 
(Fig.  168.  i.) 

The  superficial  temporal,  one  of  the  radicals  of  the  jugular' 
vein,  and  a  satellite  of  the  corresponding  artery,  is  situated 
behind  the  posterior  border  of  the  jaw,  near  the  temporo- 
maxillary  articulation,  and  buried  in  and  under  the  parotid 
gland.  It  results  from  the  union  of  the  anterior  auricular  and 
subzygomatic  veins.  The  large  anterior  auricular  receives  the 
superior  cerebral  vein,  which  leaves  the  cranium  by  the  parieto- 
temporal conduit,  just  behind  the  articulation  of  the  lower  jaw. 
The  superficial  temporal  vein  passes  through  the  temporalis  muscle, 
receiving  branches  from  it  and  from  the  external  part  of  the 
ear. 

The  subzygomatic  vein  is  divided  into  two  branches,  the  trans- 
verse, a  satellite  of  the  equivalent  artery,  and  the  masseter,  which 
anastomoses  with  the  maxillo-muscular  inferiorly,  and  with  a  large 
vein  from  the  temporalis  which  comes  through  the  sigmoid  notch, 
and  receives  the  deep  temporal  branches  of  the  internal  maxillary 
vein  superiorly. 


BRANCHES   OF    THE   JJGQLAR   VEIN.  447 

INTERNAL  MAXILLARY  VEIN. 

This,  the  other  radical  of  the  jugular,  is  a  large  vessel  situated 
between  the  pterygoid  muscles  and  the  maxillary  bone  ;  it  runs 
obliquely  upwards  and  backwards,  to  the  inner  aspect  of  the  maxil- 
lary articulation,  just  below  the  condyle  of  the  lower  jaw,  where, 
after  turning  slightly  downwards,  it  joins  the  superficial  temporal ; 
it  originates  in  the  hvbccal  vein,  near  the  superior  extremity  of  the 
buccinator.  Its  branches  are  the  Jingual,  the  inferior  dental, 
deep  temporals,  pterygoids,  and  other  satellites  of  the  branches  of 
the  internal  maxillary  artery. 

The  arrangement  of  the  buccal  vein  is  worthy  of  note.  It 
proceeds  from  the  facial  vein  at  the  anterior  edge  of  the  masseter 
muscle,  and  passes  upwards  and  backwards  under  that  muscle, 
presenting  an  enormous  dilatation  or  pouch.  Towards  the  superior 
end  of  the  buccinator  it  becomes  the  internal  maxillary  vein. 

BRANCHES  OF  THE  JUGULAR  VEIN. 
(Fig.  168.) 
The  chief  branches  entering  the  jugular  are  the  maxillo- 
muscular,  posterior  auricular,  occipital,  glosso-facial,  thyroid,  and 
cephalic.  The  maxillo-muscular  veins  are  two  in  number,  and 
correspond  to  the  branches  of  the  artery.  The  'posterior  auricular, 
which  commences  under  the  ear,  descends  over  the  parotid  gland, 
where  it  receives  numerous  branches,  and  enters  the  jugular  just 
below,  and  on  the  opposite  side  of  the  preceding.  The  occipital 
vein,  the  satellite  of  the  artery,  receives  blood  from  the  brain, 
spinal  cord,  and  muscles  about  the  poll. 

The  glosso-facial,  external  or  submaxillary  vein,  also  a  satellite, 
commences  by  two  branches  :  the  posterior  or  angular  comes  from 
the  angle  of  the  eye  ;  the  anterior  or  dorsalis  nasi,  from  the  upper 
part  of  the  nose.  It  descends  along  the  anterior  border  of 
masseter,  and  winds  round  the  lower  jaw,  between  the  artery  and 
Steno's  duct.  Below  the  pterygoideus,  at  the  antero-inferior 
border  of  the  submaxillary  gland,  it  leaves  the  artery,  and  enters 
the  jugular  at  an  acute  angle.  The  chief  branches  of  the  glosso- 
facial,  in  addition  to  a  small  lateral  nasal  vein  near  its  origin,, 
are  the  alveolar,  superior  and  inferior  coronary,  buccal,  and  sub- 
lingual veins. 

The  alveolar  vein,  or  vena  varicosa,  is  peculiar  in  form  and 
disposition,  being  buried  under  the  masseter,  between  the  zygoma 


448  ANGIOLOGY. 

and  the  alveoli  of  the  upper  molars  ;  its  anterior  extremity  opens 
into  the  facial  vein ;  posteriorly  it  cros3es  the  alveolar  tuberosity, 
and  passes  through  the  optic  fossa,  receiving  the  superior  dental, 
spheno-palatine  palatine,  and  staphyline  veins  ;  in  the  ocular 
sheath,  it  receives  the  veins  from  the  eye.  By  the  side  of  the 
ophthalmic  nerve,  it  enters  the  cranium  by  the  foramen  lacerum 
orbitale,  and  communicates  with  the  cavernous  sinus  at  the  base 
of  the  brain.      Before  this   vein  winds  round  the  alveolar  tuber- 


Tio.  168. 
Veins  of  the  face  and  neck.  1,  Glosso-facial ;  A,  Its  facial  portion  ;  2.  Jugular  ;  3,  Occipital 
4,  Cervical  portion  of  jugular  ;  o,  Superior  coronary  ;  b,  Small  labial  branch  ;  c,  Inferior  coronary 
«',  Common  coronary  trunk ;  d,  Angular  vein  of  the  eye ;  e,  Dorsal  nasal ;  e',  Lateral  nasal 
J,  Alveolar;  g,  Buccal  ;  h,  Posterior  auricular;  i,  Superficial  temporal  ;  k.  Anterior  auricular 
I,  Subzygomatic  ;  m,  Superior  cerebral— cut  ;  n,  Maxillo  muscular  ;  o  o  o,  Muscular,  oesophageal 
and  tracheal  twigs. 

osity,  it  forms  a  large  venous  reservoir,  which  diminishes  before 
entering  the  ocular  sheath.  The  use  of  this  reservoir  is  apparently 
to  prevent  congestion  in  the  cavernous  sinuses. 

The  superior  and  inferior  coronary  veins  are  the  next 
branches,  and  sometimes  they  unite  to  form  a  common  trunk. 
The  superior  gives  off  a  small  labial  branch. 


LYMPHATIC    VESSELS. 


44J? 


The  buccal  or  inferior  communicating  vein  resemlDles  the 
^ena  varicosa,  and  is  a  satellite  of  the  buccal  artery ;  being  the 
radical  of  the  internal  maxillary  vein,  we  have  described  it  with 
that  vessel. 

The  sublingual  vein  is  large,  consisting  of  two  branches,  whicV" 
unite  and  pierce  the  mylo-hyoideus  muscle. 

The  thyroid  vein,  a  large  vessel  formed  by  the  laryngeal  and 
thyroid  veins,  gains  tb'^  jugular  near  the  termination  of  the 
glosso-facial.  . 

The  cephalic  vein  enters  at  the  inferior  extremity  of  the  jugular, 
coming  from  the  internal  superficial  vein  of  the  arm ;  it  is  a 
satellite  of  the  pectoral  branch  of  the  inferior  cervical  artery,  and 
is  found  in  the  interstice  between  the  levator  humeri  and  pectoralis 
anticus  muscles. 

The  minor  branches  of  the  jugular  are  several  nameless  ones, 
"^vhich  return  blood  from  the  parotid  gland  and  cervical  muscles. 

Lymphatic  System. 
The  lymphatic  or  absorbent  system  is  connected  with  the  blood- 
vascular  system,  and  consists  of  a  series  of  tubes,  which  absorb 
and  convey  to  the  blood  certain  fluids  ;  a  number  of  glandular 
bodies  through  which  the  tubes  frequently  pass  ;  and  the  fluids 
themselves,  which  are  lymph  and  chyle. 

LYMPHATIC  VESSELS. 

These  r^re  "called  lymphatic  vessels,  because  they  convey  a  clear 
limpid  fluid,  or  absorbent  vessels,  because  fcbey  absorb  aliment- 
ary laatter.  The  absorbents  of  the  chyle  are  called  lacteal,  or 
oi:yliferous  vessels,  but  do  not  difier  from  the  rest  in  character 
or  aiiatomicai  structure.  The  lymphatics  unite  to  form  two 
large  trunks,  the  thoracic  duct,  and  the  right  lymphatic  vein, 
both  of  which  enier  the  venous  system  near  the  heart.  Delicate 
in  structure,  and  transparent,  they  are  present  in  nearly  every 
tissue  ;  and  although  more  numerous  than  the  blood-vessels,  their 
collective  capacity  is  probably  not  greater.  They  are  placed 
superficially  and  deeply  with  respect  to  the  more  solid  organs. 
The  walls  of  the  larger  vessels  consist  of  three  coats  ;  the 
external  is  composed  of  a  network  of  interlacing  areolar  tissue, 
mixed  with  fibres  of  elastic  and  smooth  muscular  tissue ,  this 
coat  ccDuects  the  vessel  with  its  surroundings.    The  middle  coat  is 

2g 


450 


ANGIOLOGY. 


thin  and  highly  elastic,  consisting  of  smooth  musculat-  fibres 
interlaced  with  areolar  and '  elastic  tissue.  The  internal  coat  is 
merely  a  basement  membrane  of  elastic  tissue,  covered  by  a 
simple  layer  of  endothelium.  The  coat  of  the  small  vessels, 
lymph  capillaries,  consists  of  membranous  and  cellular  layers. 

The  lymphatic  vessels  are  beaded  in  appearance,  due  to  the 
presence  of  valves  in  their  interior,  which  aid  the  onward  flow  of 
their  contents.  These  generally  consist  of  two.  semilunar  flaps, 
with  an  attached  convex  and  a  free  concave  border  ;  they  are 
most  numerous  in  the  proximity  of  the  glands,  and  are  always 
found  where  the  lymphatic  trunks  enter  the  blood-vessels. 

Lymphatic  vessels  may  pass  through  two  or  more  glands,  or 

they  may  enter  a  central 
trunk  without  approach- 
ing any  gland. 

LYMPHATIC    GLANDS. 

The  lymphatic  glands 
are  small,  round,  or  oval 
in  shape,  varying  in  size 
from  a  hemp  seed  to  a 
kidney  bean;  in  colour 
they  vary  much,  but  are 

cul»  of  cortical  pc;rtion  ;  c,  Trabec^I^'oVmed^lIIr;';;;  ^.^^^^^^^^  ^Ome  modifica- 
tion;  d  e.  Lymphoid  contents  of  locaU  ;  //,  Afferent  ^^0'^  of  pale  red,  reddish 
vessels;   .  ,,  Their  coafiuence.  leading  to  k.  the  efferent     b^OWn,    Or    groy.         They 

consist  of  a  oort-ical  sub- 
stance covered  externally  by  a  fibrous  capsule  which  sends  trabecu- 
lae  within  the  gland,  dividing  it  into  numerous  polygonal  cavities, 
caU6d  loculi  or  alveoli,  which  are  fiUed  with  a  whitish  pulp 
containing  cells  and  nuclei,  identical  in  character  with  lymph 
corpuscles  ;  the  deeper  part  of  the  gland  is  called  the  medullary 
substance;  it  also  contains  loculi  and  lymphoid  tissue.  The 
loculi  are  lined  by  very  delicate  processes  given  off  from  the 
trabeculag,  which  divide  them  into  very  minute  cavities  'com- 
municating with  each  other,  forming  a  spongy  texture  enclosing 
the  lymphoid  tissue.  The  vessels,  just  before  Veaching  the  glands, 
dmde  into  the  afferent  vessels,  or  vasa  afferentia,  which  enter  the 
gland  ;  these  subdivide  into  intricate  plexuses,  which  open  into 
the  spongy  cavities,  whence  originate  vessels  which  lead  to  those 


Fig.  1C3. 
Section  of  a  Lymphatic  Gland,    o  a,  Capsule  ;  6  ft,  Trabe- 


THORACIC    DUCT.  451 

emanating  from  and  leaving  the  gland,  the  vasa  efferentia,  or 
efferent  vessels.  The  efferent,  fewer  but  larger  than  the  afferent, 
after  a  short  course  unite  to  form  larger  vessels.  Sometimes  a 
depression  on  the  surface  of  a  gland,  the  Idlus,  marks  the  spot 
where  the  efferent  vessels  leave  it. 

The  closed  glands  of  the  stomach,  intestines,  tongue,  &c.,  con- 
sist of  a  material  resembling  that  of  the  lymphatic  glands,  and 
which  has  been  termed  lymphoid  or  adenoid  tissue  ;  it  -consists 
mainly  of  retiform  connective  tissue  and  colourless  corpuscles. 

LYMPH    AND    CHYLE. 

Lymph  is  a  colourless  fluid,  containing  a  number  of  objects 
which  resemble  almost  perfectly  the  white  corpuscles  of  the  blood ; 
these  are  the  lymph  corpuscles,  and  they  are  believed  to  be  formed 
in  lymphoid  tissue,  but  notably  in  the  lymphatic  glands,  and 
conveyed  thence  by  the  efferent  vessels. 

Chyle  is  a  milky  fluid  found  in  the  lacteals  or  lymphatic 
vessels  of  the  intestines  during  digestion;  it  contains  corpuscles 
similar  to  those  of  the  lymph.  Since  both  t\\e  lacteal  and  pos- 
terior lymphatic  vessels  lead  to  the  great  lymphatic  trunk,  or 
thoracic  duct,  it  follows  that  the  lymph  and  the  chyle  become 
mixed. 

-       THORACIC    DUCT. 
(Fig.  170.) 

This,  the  largest  and  longest  lymphatic  vessel,  receives  all  the 
others,  except  those  of  the  right  anterior  extremity,  and  right 
side  of  the  head,  neck,  and  thorax ;  it  originates  in  the  lumbar 
region  between  the  posterior  aorta  and  vena  cava,  by  a  very 
irregular  dilatation  called  the  receptaculum  chyli,  or  reservoir  of 
Pecquet,  into  which  flow  the  contents  of  the  neighbouring  vessels. 
From  the  anterior  aspect  of  this  reservoir,  the  duct  proceeds  for- 
wards on  the  right  side  of  the  vertebral  column,  enters  the 
thoracic  cavity  through  the  aortic  hiatus  of  the  diaphragm,  passing 
along  the  vertebrae  until  it  reaches  about  the  sixth  dorsal,  where 
it  curves  downwards  to  the  left  side,  over  the  base  of  the  heart, 
and  towards  the  beginning  of  the  anterior  vena  cava,  in  most  cases 
terminating  in  the  jugular  confluent  about  the  anterior  border 
of  the  first  rib.  Its  orifice  is  dilated  and  guarded  by  a  valve, 
which  prevents  the  influx  of  blood ;  it  may  be  double,  when  we 


452 


ANGIOLOGT. 


"have  a  right  and  left,  or  double  at  its  origin  only ;  or  it  may  be 
single  at  its  origin,  then  bifid  for  a  short  distance,  again  forming 
a  single  trunk  ;  it  contains  a  few  valves. 

The  lymphatics,  which  form  the  affluents  of  the  thoracic  duct, 
may  be  divided  into  five  groups,  comprised  within  the  following 
divisions  of  the  body  : — 

Posterior  region.  I  Thoracic  viscera. 

Digestive  viscera.  I  Thoracic  walls. 

Anteiior  region. 


Fiu.  170. 

Thorax  laid  open  on  the  right  side— the  lungs  beicg  removed.    1,   Part  of  posterior  aorta ; 

2,  Trachea  divided  ;  o  a,  Kight  and  left  branches  of  origin  of  thoracic  duct  (double  posteriorly  in 

this  instance) ;  6,  Point  of  union  of  the  branches ;  c  c,  Loops  leaving  and  rejoining  the  duct ; 

d,  Point  of  discharge  of  the  duct ;  e,  Cervical  lymphatic  vessel ;  e',  Its  termination  in  the  duct. 


POSTERIOR    REGION. 

This  embraces  tlie  lymphatics  of  the  posterior  extremity,  pelvis, 
abdominal  walls,  and  organs  of  tbe  pelvic  region.  They  all 
converge  to  a  large  group  of  glands,  the  sublumbar,  presenting, 
however,  at  different  parts  of  their  passage,. other  groups.  "We 
note  the  followins: : — 


Sublumbar. 
Deep  inguinal. 
Superficial  inguinal. 


Pophteal. 

Iliac. 

Precrural. 


The  sublumbar  glands  occupy  the  sublumbar  region,   resting 
in  the  angles  formed  by  the  bifurcation    of  the   posterior  aorta. 


POSTERIOR    REGION.  •         453 

€xt€fliding  as  far  forward  as  the  posterior  mesenteric  and  sper- 
matic arteries.  This  group  receives  the  lymphatics  of  the  pelvis, 
the  eiFerent  branches  from  the  deep  inguinal,  and  iliac  glands, 
branches  from  the  rectum,  double  colon,  and  spermatic  cord. 
The  numerous  different  branches  of  the  sublumbar  glands,  after 
forming  one  or  more  trunks,  terminate  in  the  receptaculum  chyli. 

The  deep  inguinal  glands  are  formed  by  a  considerable  num- 
ber of  lobes  lodged  under  the  crural  aponeurosis  and  arch,  in  the 
interstices  between  the  adductor  muscles  of  the  thigh,  along  with, 
and  to  the  inner  aspect  of,  the  crural  vessels.  The  group  is 
elongated,  and  superficial  exteriorly,  reaching  almost  to  the 
anterior  pubic  border.  The  colour  of  the  lobes  varies  from  grey 
to  brown,  or  almost  black.  The  afferent  vessels  are  formed  by 
the  superficial  lymphatics,  which  accompany  the  internal  saphenic 
vein,  and  by  satellites  of  the  deep  blood-vessels.  The  efferent 
branches  of  this  group  pass  into  the  sublumbar  glands,  entering 
the  abdomen  in  company  with  the  external  iliac  vessels. 

The  superficial  inguinal  glands  are  placed  in  front  of  the 
inguinal  ring,  at  the  side  of  the  sheath.  They  are  oblong,  and 
consist  of  ten  or  twelve  lobes.  The  afferent  vessels  are  numerous, 
and  receive  the  lymph  from  the  internal  part  of  the  thigh,  the  sheath, 
scrotum,  and  inferior  abdominal  walls.  The  efferents,  larger,  but 
less  numerous,  pass  up  the  inguinal  canal  in  company  with  the 
external  pudic  artery,  and  terminate  in  the  deep  inguinal  glands. 

The  small  popliteal  glands  consist  of  from  three  to  five  lobes, 
situated- just  behind  the  great  sciatic  nerve  and  gastrocnemius 
muscle,  and  between  the  adductor  magnus  and  biceps  rotator 
tibialis,  near  the  femoro-popliteal  artery.  They  receive  the  lymph- 
atics from  the  posterior  part  of  the  haunch  and  from  the  neigh- 
bourhood of  the  hock.  The  efferents  join  the  deep  inguinal 
glands,  passing  through  the  muscular  interstices  of  the  thigh. 

The  iliac  glands  consist  of  five  or  six  lobes,  which  form  a  soft 
yellow  group,  situated  in  the  triangular  space  between  the  two 
branches  of  the  circumflex  ilii  artery.  They  receive  the  efferents 
from  the  precrural  glands,  and  numerous  deep  lymphatics  from 
the  abdominal  walls.  The  five  or  six  efferent  vessels  follow  the 
circumflex  artery,  and  terminate  in  the  sublumbar  glands. 

The  precrural  glands  rest  on  the  inner  side  of  the  anterior 
border  of  the  tensor  fascia  lata,  upon  the  circumflex  artery,  and 
constitute  a  small  elongated  mass,  composed  of  about  twelve 
lobes.      It  receives  the  lymphatics  from  the  anterior  and  internal 


*54  ANGIOLOGY. 

part  of  the  thigh.  Its  three  or  four  efferents  are  very  large  ;: 
passing  up  the  internal  face  of  the  fascia  lata  muscle,  they  eater 
the  abdominal  cavity  towards  the  angle  of  the  haunch,  and  join 
the  iliac  glands. 

ABDOMINAL   VISCERA. 

The  lymphatics  of  the  rectum  and  Jloating  colon.  There  are 
two  or  three  lobes  at  the  base  of  the  tail  on  each  side  of  the 
sphincter,  a  series  of  glands  along  the  small  curve  of  the  viscera, 
and  the  mesenteric  glands,  comprised  between  the  layers  of  the 
mesentery,  receiving  the  radical  vessels  which  arise  in  the  mucous 
and  fleshy  coats  of  the  intestine  generally.  Their  efferent  vessels 
frequently  traverse  the  glands  placed  on  the  passage  of  the 
blood-vessels,  and  reassemble  towards  the  origin  of  the  posterior 
mesenteric  artery  by  numerous  large  branches,  which  join  the 
divisions  of  the  sublumbar  lymphatics,  or  those  of  the  double 
colon. 

The  lymphatics  of  the  large  colon. — Upon  this  viscus  a  double 
chain  of  glands  accompanies  the  colic  arteries.  Numerous  small 
lobes,  at  short  distances  from  the  principal  glands,  are  dis- 
seminated over  the  lateral  branches  of  the  blood-vessels.  The 
lymphatics  emanating  from  the  coat  of  this  intestine  pass  for  the 
most  part  into  these  small  lobes,  afterwards  joining  the  principal 
glands,  whence  they  emerge  as  numerous  large  satellites  of  the 
colic  blood-vessels.  These,  and  the  lymphatics  of  the  small 
mtestine,  unite  to  form  the  two  great  mesenteric  trunks,  which, 
with  the  efferent  branches  of  the  sublumbar  glands,  form  the 
reservoir  of  Pecquet. 

The  ly77i]jhatics  of  the  ccecum. — The  glands  of  this  organ  are 
found  along  the  passage  of  the  csecal  arteries,  constituting  a  series 
not  so  close  as  those  of  the  great  colon,  into  which  are  received 
the  lymphatic  vessels  of  the  membranes  of  the  csecum.  These, 
on  leaving  the  glands,  form  larger  branches,  which  are  satellites 
of  the  blood-vessels,  and  enter  the  same  trunk  as  those  of  the 
small  intestine. 

The  lymphatics  of  the  small  intestine. — The  lymphatic  glands, 
which  receive  the  lacteals  of  this  intestine,  are  about  thirty  iii 
number,  of  a  grc-j  colour,  large,  fusiform,  very  compact,  and  often 
bifurcated  at  their  superior  extremity.  They  are  lodged  in  the 
mesentery,    near   the  origin    of  the  anterior   mesenteric   artery. 


THORACIC    VISCERA.  455 

Bvssides  these  larger  glands,  there  are  about  fifteen  smaller  lobes 
dispersed  along  the  course  of  the  ilio-csecal  artery. 

The  lymphatic  vessels  form  a  large  network,  converging  from 
the  visceral  walls  to  the  mesenteric  glands,  which  they  enter  at 
the  superior  extremity  of  tbe  mesentery.  The  efferent  branches, 
usually  two  or  three  from  each  gland,  unite  to  form  larger  ones, 
which  finally  join  the  intestinal  branch  of  the  receptaculum  chyli. 

The  lymphatics  of  the  stomach. — The  glands  of  the  stomach 
are  divided  into  two  classes ;  a  large  series,  situated  in  the  lesser, 
and  a  chain  of  smaller  ones,  distributed  along  the  greater  curva- 
ture, and  attached  to  the  gastro-colic  omentum.  The  deep  and 
superficial  lymphatics  of  the  stomach  enter  these  glands,  and 
collecting  on  the  blood-vessels,  pass  up  towards  th'e  greater  cul- 
de-sac  near  the  cceliac  axis,  where  they  anastomose  with  branches 
from  the  spleen  and  liver,  forming' large  flexuous  trunks,  some  of 
which  enter  the  thoracic  duct,  while  others  pass  backwards  to  the 
trunks  of  the  intestinal  lymphatics. 

The  lymphatics  of  the  spleen.— T}iose  of  the  spleen  are  deep 
and  superficial  ;  the  former  occurring  in  the  parenchyma,  the 
latter  on  the  surface.  They  all  pass  to  the  branches  of  the 
vessels  in  the  hilus,  enter  numerous  groups  of  glands,  and  are 
dispersed  along  the  blood-vessels,  anastomosing  with  the  lymphatics 
of  the  stomach  and  liver. 

The  lymiohatics  of  the  liver  consist  of  a  deep  series  in  the 
parenchyma  of  the  gland,  and  a  networlL  of  superficial  ones  on 
the  capsule.  They  assemble  towards  the  posterior  fissure,  and, 
entering  a  group  of  small  glands,  pass  into  a  much  larger  group 
situated  between  the  trunk  of  the  vena  porta  and  the  pancreas. 
Their  efferents  anastomose  with  those  of  the  stomach  and  spleen. ^ 

THORACIC    VISCERA. 

In  the  thorax  there  are  three  groups  of  lymphatic  glands  ;  a^ 
series  of  small  ones  in  the  posterior  mediastinum,  which  receive 
the  lymphatic  vessels  of  the  posterior  part  of  the  oesophagus;  the 
bronchial  glands,  ^vhich  axe  situated  at  the  angle  of  bifurcation 
of  the  trachea,  stretching  a  short  distance  into  the .  parenchyma 
of  the  lungs,  and  receiving  their  lymphatic  vessels  ;  two  series  ot 
glands,  extending  along  the  infero-lateral  face  of  the  trachea 
from  the  base  of  the  heart  to  the  first  rib,  receiving  the  lymphatics 
from  the  pericardium  and  heart,  and  portions  of  the  trachea  and 


456  ANGIOLOGY. 

oesophagus.      The   efferent   vessels   unite   to   form   two  or  three? 
trunks  which  enter  the  thoracic  duct  in  different  places. 

THORACIC    WALLS. 

In  this  group  there  are  also  three  sets  ;  a  double  chain  of  small 
round  glands,  situated  on  each  side  of  the  dorsal  vertebrae  above 
the  intercostal  spaces,  and  under  the  costal  pleura ;  a  large  gland- 
ular mass,  resting  on  the  xiphoid  cartilage,  just  behind  the  heart 
and  in  front  of  the  inferior  part  of  the  diaphragm ;  and  a  group 
of  rudimentary  glands,  which  accompany  the  internal  thoracic- 
arteries. 

The  lymphatics  of  the  diaphragm,  after  receiving,  it  is  said^ 
those  from  the  convex  face  of  the  liver,  enter  the  glands  at  the 
base  of  the  diaphragm,  leaving  them  by  numerous  branches  which, 
accompany  the  internal  thoracic  arteries,  and  either  join  the 
anterior  extremity  of  the  thoracic  duct  or  the  great  lymphatic 
vein,  usually  after  passing  through  the  prepectoral  glands.  They 
receive  the  lymphatics  from  the  inferior  part  of  the  intercostal 
spaces.  The  other  lymphatic  vessels  of  the  thoracic  walls  ruu 
upwards  in  the  intercostal  spaces,  and  enter  the  chain  of  glands 
along  the  sides  of  the  dorsal  vertebraj,  forming  two  canals,  which. 
pass  forwards  to  enter  the  anterior  portion  of  the  thoracic  duct. 

ANTERIOR    REGION, 

The  lymphatics  of  the  head,  neck,  and  anterior  extremity  are 
directed  to  the  entrance  of  the  thorax,  where  there  is  a  group  of 
glands  termed  the  prepectoral,  which  may  be  regarded  as  the 
lymphatic  centre  of  the  whole  anterior,  as  the  sublumbar  is  of 
the  posterior  part  of  the  body.  Before  the  vessels  reach  this 
point  of  convergence,  they  are  intercepted  by  one  or  more  of  four 
other  glandular  groups.  We  have  in  this  region  the  following 
groups  of  glands  : — 

Prepectoral.  I  Submaxillary. 

Guttural.  I  Prescapular. 

Brachial. 

The  prepectoral  glands  are  found  on  each  side  of  the  ter- 
minal extremity  of  the  jugulajr  veins,  inside  the  inferior  border  of 
the  scalenus ;  they  are  massive,  passing  into  the  chest  under  the 
brachial  vessels,  and  along  the  internal  aspect  of  the  first  pair  of 


ANTERIOR   REGION.  457 

ribs.  Entering  these  glands  are  the  emerging  lymphatic  branches 
of  the  prescapular  and  brachial  glands,  those  from  the  guttural 
glands,  which  descend  the  trachea  with  the  carotid  artery,  as  well 
as  most  of  those  which  accompany  the  internal  thoracic  vessels. 
They  afford  numerous  short  and  voluminous  branches,  those  of 
the  right  side  forming  the  lymphatic  vein ;  those  of  the  left 
joining  the  thoracic  duct,  at  times  reaching  the  anterior  cava  by 
a  separate  trunk. 

The  guttural  glands  are  numerous,  and  attached  slightly  to 
each  other.  They  are  disposed  in  an  elongated  mass  which 
occupies  the  lateral  wall  of  the  pharynx,  below  the  guttural 
pouch,  reaching  almost  to  the  thyroid  gland.  They  receive  all 
the  lymphatics  of  the  head,  some  directly  from  the  base  of  the 
tongue,  soft  palate,  walls  of  the  larynx  and  pharynx ;  others  are 
efferents  from  the  submaxillary  glands,  and  from  a  lobe  lodged  in 
the  substance  of  the  parotid  gland.  The  efferents  form  four  or 
five  large  branches,  which  descend  the  trachea  singly,  or  united 
into  a  bundle  which  follows  the  carotid;  numerous  elongated 
glands  receive  the  radical  lymphatics  from  the  cervical  portion  of 
the  trachea  and  oesophagus.  On  arriving  at  the  entrance  of  the 
thorax,  the  efferents  enter  the  prepectoral  glands;  branches 
sometimes  pass  directly  to  the  thoracic  duct  on  the  left,  or  the 
lymphatic  vein  on  the  right  side. 

The  submaxillary  glands  are  a  fusiform  mass  situated  at  the 
base  of  the  tongue,  between  the  digastric  and  mylo-hyoid  muscles, 
and  a  little  above  the  glosso-fascial  artery  ;  they  receive  the 
lymphatic  vessels  from  the  tongue,  cheeks,  lips,  nose,  and  nasal 
cavities,  the  efferent  vessels  going  to  the  guttur^al  glands. 

The  prtsca-pidar  glands  form  by  their  union  a  chain  running 
in  the  course  of  the  ascending  branch  of  the  inferior  cervical  artery, 
under  the  internal  face  of  the  levator  humeri,  and  descending 
almost  to  tln3  attachment  of  the  sterno-maxillaris.  The  cervical 
lym^jJiatics,  superficial  and  deep,  mostly  enter  this  glandular 
chain,  as  well  as  those  from  the  breast,  and  a  part  of  those  from 
the  shoulder ;  their  efferents,  short  and  voluminous,  pass  to  the 
prepectoral  glands. 

The  brachial  glands,  situated  under  the  shoulder,  consist  of 
two  groups ;  one  is  situated  near  the  elbow  to  the  inside  of  the 
inferior  extremity  of  the  humerus,  receiving  the  lymphatic  vessels 
of  the  foot  and  fore-arm,  which  accompany  the  superficial  veins, 
or  pass  up  the  interstices  of  the  muscles  with  the  deep  vessels  ; 


458  COMPARATIVE    ANGIOLOGY. 

the  other  is  disposed  in,ja  mass  behind  the 'brachial  vessels,  near 
the  common  insertion  oF  the  latissimus  dorsi  and  teres  internus ; 
it  receives  nine  or  ten  lymphatic  branches  from  the  shoulder  and 
arm.,  The  efferents  accompany  the  brachial  vessels,  and  enter 
the  prepectoral  glands. 

LYMPHATIC    VEIN. 

The  second  principal  trunk  is  the  lymphatic  vein,  or  ditctiLs 
lymphaticus  dexter,  a  vessel  measuring  in  length  from  three- 
quarters  to  one  inch,  situated  near  the  junction  of  the  jugular 
veins,  and  terminating  m  their  confluent ;  it  is  also  guarded  by 
a  valve,  and  receives  the  lymphatic  vessels  from  the  right  anterior 
extremity,  and  the  right  side  of  the  head,  neck,  and  thorax. 


COMPARATIVE  ANGIOLOGY. 
EUMINANTIA. 
In  the  heart  of  the  ruminant,  the  most  prominent  feature  --s  the  pr&sence  of 
the  cardiac  bones  (see  p.  105),  which  appear  in  adult  life.  They  are  two  in 
number,  and  lie  between  the  auriculo-ventricular  rings  and  the  common  aorta 
on  the  left,  the  pulmonary  artery  on  the  right  side.  There  is  a  third  longi- 
tudinal furrow  running  down  the  wall  of  the  left  ventricle  posteriorly.  The 
furrows  contain  more  fat  as  a  rule  than  those  of  the  horse's  heart.  There 
are  usually  nme  aortic  intercostals,  and  three  anterior  ones,  or  twelve  in  all. 
The  cceliac  axis  reaches  the  rumen  just  behind  the  cesophagus.  On  the  left  is 
given  off  the  artery  of  the  reticulum,  which  passes  to  the  left  of  the  esophagus, 
and  divides  into  a  superior  and  an  inferior  branch.  Just  posterior  to  this  the 
splenic  artery  arises,  and  still  farther  back  the  hepatic,  which  supplies  the  liver 
and  gall-bladder,  giving  off  the  duodenal  branch,  which  anastomoses  with  the 
superior  artery  of  the  abomasum,  and  the  anterior  mesenteric.  The  terminal 
branch  of  the  cceliac  axis  divides  and  forms  a  superior  and  an  inferior  artery 
of  the  psallcrium  ayid  ahomasum,  which  pass  along  the  surfaces  of  these  cavities, 
the  former  anastomosing  with  the  duodenal.  The  superior  and  inferior 
arteries  of  the  rumen  are  placed  in  the  longitudinal  groove,  the  former  usually 
arises  from  the  splenic,  running  backwards ;  the  latter  is  generally  given  off 
by  the  artery  of  the  reticulum,  and  runs  forwards  and  between  the  anterior 
sacs,  to  gain  the  inferior  surface,  where  it  passes  backwards  and  reaches  the 
groove  between  the  conical  sacs,  anastomosing  with  the  superior  vesseL 

The  anterior  mesenteric  artery  divides  into  two  branches,  an  anterior  for  the 
small,  and  a  posterior  for  the  largo  intestine.  The  former  resembles  that  of 
the  horse  in  its  distribution  ;  the  latter  instead  of  following  the  fiexures 
of  the  colon  gives  ^off  branches  which  cross  them.  The  posterior  mesenteric 
artery  is  small.  The  middle  sacral  artery  is  very  large,  giving  off  the  arteries 
of  the  tail  ;  it  may  be  regarded  as  the  continuation  of  the  posterior  aorta,  the 
lateral  sacrals  being   somewhat    rudimentary,  and    their    terminal  branches 


RUMINANTIA.  459 

-wanting.  In  the  smaller  ruminants,  branches  from  the  deep  femoral  take  the 
place  of  the  obturator  and  iliaco-femoral  arteries  which  are  wanting  ;  in  the  ox 
they  are  rudimentary.  The  uterine  artery  is  very  large,  arising  from  a  trunk 
common  also  to  the  umbilical. 

The  arteries  of  the  pelvic  limb  offer  no  deviation  from  those  in  tjie  typical 
animal,  of  sufficient  importance  to  merit  description  in  an  elementary  work, 
until  we  descend  to  the  tarsal  joint,  below  which  the  arteries,  like  the  other 
appendicular  structures,  present  certain  comparative  features  worthy  of  notice. 
The  great  metatarsal  artery,  with  two  veins,  occupies  the  mediae  groove  on  the 
front  of  the  metatarsus,  passes  through  the  notch  between  the  distal  articulai 
surfaces,  and  gains  the  back  of  the  digit  as  the  common  digital  artery.  Above 
the  distal  ends  of  the  ossa  suffraginis  it  divides  into  external  and  internal 
ungual  arteries,  each  of  which  gains  the  inner  aspect  of  its  respective  digit,  and 
enters  the  distal  phalanx,  where  it  behaves  similarly  to  the  plantar  ungual  of 
the  horse.  The  lateral  digital  arteries  pass  down  the  outer  sides  of  the  digits, 
that  of  the  external  digit  being  formed  by  the  interosseous  plantar  and  a 
transverse  communicating  branch,  while  that  of  the  internal  digit  is  given  off 
by  the  great  metatarsal  artery. 

The  anterior  aorta,  it  has  been  stated,  is  wanting  ;  if  it  is  present  it  is 
remarkably  short.  If  it  be  absent,  we  must  describe  the  brachials  as  arising 
from  the  common  aorta.  The  dorsal  and  vertebral  arteries  arise  by  a  common 
trunk,  the  former  furnishing  a  branch  which  takes  the  place  of  the  superior 
cervical  artery,  which  is  wanting.  The  vertebral  artery  is  large,  and  does  not 
inosculate  with  the  occipital,  but  terminates  in  muscular  branches.  The 
humeral  artery  is  small,  as  are  most  of  its  branches  ;  the  chief  artery  supplying 
the  muscles  of  the  posterior  brachial  region  is  the  scapulo-humeral  branch  of 
the  subscapular  artery.  The  radio-palmar  artery  forms  an  inferior  arch,  as  in 
the  horse,  from  which  are  given  off  three  interosseous  palmar s  and  one  dorsal; 
of  the  former  the  internal  is  the  largest  and  most  constant  ;  the  dorsal  or 
anterior  interosseous  artery  gains  the  front  of  the  limb,  anastomosing  superiorly 
with  the  anterior  radial  artery,  while  inferiorly  it  occupies  the  vertical  groove 
in  the  metacarpus,  and  inosciilates  with  a  recurrent  branch  of  the  great  meta- 
carpal artery,  which  passes  between  the  articulations  at  the  distal  end  of  the 
bone.     The  arteries  of  the  digit  resemble  in  the  main  those  in  the  pelvic  limb., 

The  carotid  arteries  arise,  as  in  the  horse,  by  a  primitive  trunk  from  the 
brachio-cephalic  artery  ;  they  break  up  at  the  head,  forming  the  external 
carotid,  and  a  small  occipital  artery  :  the  internal  carotid  is  wanting,  its 
function  being  performed  by  the  encephalic  artery.  The  occipital  artery  enters 
the  cranium  by  the  condyloid  foramen,  passes  backwards  and^inosculates  with 
the  lateral  artery  of  the  spinal  cord,  at  about  the  level  of  the  internal  foramen 
of  the  atlas  ;  a  branch  given  off  from  this  union  passes  out  through  the  fora- 
men to  supply  the  muscles  of  the  poU.  The  lingual  artery  is  given  off  by  the 
external  carotid,  and  the  former  gives  off  the  sublingual  branch.  The  mustoid 
artery  of  the  horse  is  represented  by  a  branch  of  the  posterior  auricular.  In 
the  smaller  ruminants  the  coronary  arteries  of  the  lips  are  formed  by  the  bifui-- 
tation  of  the  transverse  facial,  a  branch  of  the  superficial  temporal  artery. 

The  internal  maxillary  artery  has  no  pterygoid  foramen  to  pass  through  in 


460  COMPARATIVE    ANGIOLOGY. 

uny  of  the  domesticated  rummants  ;  some  of  its  branches,  however,  lead  to  the 
formation  of  structures  interesting  to  the  anatomist  ;  these  are  the  arterial 
plexuses,  or  retia  mirabilia,  the  largest  of  which  is  formed  inside  the  cranium 
by  branches  from  the  internal  maxillary  artery.  One  of  these  branches,  the 
spheno-spinal,  enters  the  cranium  by  the  foramen  ovale,  and,  as  a  rule,  two 
arteries  of  the  rete  enter  by  the  anterior  common  foramen  ;  the  first  of  these 
inclines  forwards,  the  two  latter  backwards.  The  three  arteries  anastomose  by 
forming  a  small  and  intricate  plexus  known  as  the  cranial  rete  mirahile;  it  is 
situated  at  the  side  of  the  sella  turcica  of  the  sphenoid  bone,  communicating 
with  its  fellow  posteriorly,  and  giving  off  superiorly  the  encephalic  artery,  a 
branch  considered  by  Chauveau  to  be  "  completely  analogous  to  the  intrar 
cranial  portion  of  the  internal  corotid  in  the  solipede."  From  this  artery  are 
given  ofif  the  cerebral  branches,  anterior,  middle,  and  posterior  ;  the  last 
passing  backwards,  forms  a  convergent  anastomosis  with  its  fellow,  thua 
constituting  the  basilar  trunk  leading  to  the  middle  spinal  artery.  Another 
arterial  plexus  is  found  on  the  ophthalmic  artery  just  where  the  arteries  of 
the  eye  are  given  off.  The  glosso-facial  artery  is  found  only  in  the  larger 
ruminants. 

Veins. 

The  sube^taneous  abdominal  vein  is  very  large  in  the  ox,  the  subcutaneous 
thoracic  being  proportionally  small.  The  saphenic  veins  differ  from  those  of 
the  horse,  the  external  one  being  larger  than  the  internal.  The  jugular  vein, 
is  large,  and  there  is  a  small  accessory  jugular  which  varies  much  in  size, 
originating  in  the  occipital  vein,  and  joining  the  great  jugular  near  its  termi- 
nation.    The  angular  vein  of  the  eye  is  very  prominent  in  small  ruminants. 

The  digital  veins  of  the  posterior  limb  are  three  in  number,  an  anterior  or 
common  one  between  the  digits,  formed  by  twigs  from  the  solar  plexuses  of 
both,  and  two  lateral  ones  placed  on  the  outer  sides  of  the  digits.  There  are 
usually  five  metatarsal  veins  ;  two  anterior  deep  ones  which  accompany  the 
great  metatarsal  artery  ;  an  anterior  superficial  one,  which  forms  one  root  of 
the  external  saphenic  ;  an  internal  and  external  posterior  vein,  which  pass 
upwards  over  the  tarsus,  and  assist  i;i  forming  the  saphenic  veins.  In  the 
anterior  limb  there  is  a  fourth  or  posterior  digital  vein,  which  accompanies  the 
common  digital  and  internal  metacarpal  arteries. 

The  Lymphatics. 
In  the  large  ruminants  the  thoracic  duct  not  only  exhibits  great  complexity 
of  form,  but  it  is  also  extremely  variable,  being  sometimes  double  throughout 
its  extent.  Some  complexity  generally  exists  near  its  anterior  termination.  It  ia 
more  deeply  seated  than  that  of  the  horse,  lying  between  the  right  upper  part 
of  the  aorta  and  the  vertebral  column,  buried  in  a  quantitj'  of  fat.  It  does  not 
pass  through  the  aortic  hiatus,  but  has  an  opening  in  the  diaphragm  for  itsel£ 

OMNIVORA. 
In  the  hog  the  branches  of  the  posterior  tsDrta  call  for  no  remark,  since  they 
resemble  those  of  the  horse,  excepting  the  mesenteric  arteries,  which  are  distri- 
buted somewhat  like  those  of  the  ruminant.     After  giving  off  the  gluteal  and 


OMNIVORA C  ARNIVORA.  461 

umbilical  branches,  the  internal  iliac  artery  is  apparently  continued  by  the 
internal  pudic,  which  gives  off  the  haemorrhoidal  artery  to  supply  the  urinary 
and  genital  organs  of  the  region,  and  the  rectum  posteriorly,  and  finally  the 
cavernous  arteries. 

The  external  iliac  artery  resembles  in  its  distribution  that  of  the  ruminant. 

The  anterior  aorta  is  wanting,  the  brachial  trunks  arising  from  the  common 
aorta.  The  vertebral,  dorsal,  and  subcostal  arteries  of  the  right  side  are  given 
off  by  a  branch  which  itself  appears  to  represent  the  superior  cervical  artery. 
A  branch  from  the  subscapular  artery  is  the  analogue  of  the  deep  humeral  in 
the  horse  ;  the  rest  of  the  circulation  of  the  anterior  limb  is  mostly  like  that 
of  the  ruminant. 

The  carotid  arteries  arise  singly  from  the  brachio-cephalic  trunk  ;  They  bre.ak 
up  like  those  of  the  horse.  There  is  no  cerebrospinal  branch  of  the  occipital 
artery.  The  internal  carotid  enters  the  cranium  by  the  foramen  lacerum  posti- 
cum,  and  forms  a  rete  mirabile,  assisted  by  the  ophthalmic.  The  basilar  artery  is 
formed  as  in  the  ruminant.  The  external  carotid  extends  to  the  maxillary  hiatus, 
where  it  breaks  up — i.e.,  the  internal  maxillary  artery  is  in  thi.s  animal  con- 
sidered as  part  of  the  carotid.     The  lingual  artery  is  separate  from  the  facial. 

The  veins  call  for  little  remark.  What  we  have  said  of  tlie  jugular  and 
saphenic  veins  of  the  ruminant  is  also  applicable  here.  The  superficial  veins 
in  the  hog  are  for  the  most  part  buried  in  an  exceedingly  thick  layer  of  fat. 

The  thoracic  duct  usually  opens  into  the  left  jugular  vein,  near  its  termina- 
tion. It  sometimes  divides  anteriorly  and  reunites,  forming  a  cavity  which 
receives  the  terminal  lymph  vessels. 

CARNIVORA. 

The  heart  in  carnivora  is  extensively  related  with  the  sterniim,  the  apex  being 
directed  backwards.  In  shape  the  organ  is  very  bluntly  ovoid.  There  are  no 
well-defined  6ronc/iia^  arteries,  but  several  oesophageals  proceeding  direct  from  the 
aorta,  in  the  posterior  mediastinum  ;  some  of  these  give  off  bronchial  branches. 

The  coeliac  axis  divides  into  the  three  typical  branches,  but  there  is  no  dis- 
tinct right  and  left  division  of  the  gastric  artery.  There  is  given  off  a  'pancre- 
atico-duodenal  branch  from  the  hepatic  which  anastomoses  with  the  great 
mesenteric  artery.  Near  the  latter  a  vessel  arises  which  divides,  supplying  the 
diaphragm  anteriorly  and  the  sublumbar  region  posteriorly. 

The  internal  iliac  arteries  are  somewhat  separated  from  the  external  ones,  the 
umbilicals  being  given  off  from  their  common  trunk.  They  divide  into  two 
chief  branches,  which  may  be  considered  representatives  of  the  internal  pudic 
and  gluteal  arteries  of  the  horse;  the  first  of  these  calls  for  no  special  comment, 
the  second  passes  through  the  great  sciatic  notch  with  the  great  sciatic  nerve, 
and  becomes  lost  in  the  gluteal  and  femoral  muscles,  first  giving  off  spinal 
branches  ;  the  coccyx  is  supplied  by  branches  of  the  middle  sacral  artery. 

The  branches  of  the  external  iliac  artery  present  few  deviations  of  importance. 
The  circumflex  ilii  comes  direct  from  the  aorta.  The  posterior  tibial  artery  is 
rudimentary,  while  the  anterior  one  gives  off  a  large  tarsal  branch,  and  descends 
in  the  third  intermetatarsal  space,  inclining  backwards,  and  forming  a  plantar 
arch  underneath  the  flexor  tendons  ;  from  this  arch  are  given  off  three  diqilal 


462  COMPAEATIVE    ANGIOLOGY. 

or  plantar  arteries,  which  are  distributed  like  those  of  the  superficial  palmar 
arch  in  the  anterior  limb. 

The  brachial  arteries  in  the  main  resemble  those  of  the  hog.  The  vertebral 
inosculates  with  the  ramus  anastomoticus ;  it  supplies  many  cervical  branches, 
the  superior  cervical  artery  being  both  small  and  short.  The  humeral  artery 
(rives  ofif  branches  resembling  those  described  in  the  tj^ical  animal,  but  it 
terminates  by  dividing  into  radial  and  cubital  arteries,  the  presence  of  the 
anterior  radial  being  merely  indicated.  The  cubital  artery  gives  off  the  inter- 
osseous '  which  divides  under  the  pronator  quadratus,  into  anterior  and  posterior 
branches  ;  the  former  passes  between  the  radius  and  the  ulna,  forms  a  carpal 
plexus,  and  supplies  the  digits  anteriorly  ;  the  latter  is  the  larger,  and  in  the 
region  of  the  carpus  divides  into  a  superficial  and  a  deep  branch ;  the  first 
assists  with  the  cubital  in  forming  the  superficial  palmar  arch,  which  is  chiefly 
formed  by  the  inosculation  of  the  cubital  and  radio-palmar  arteries  ;  the  deep 
Tjranch  helps  with  the  radial  to  form  the  deep  palmar  arch,  underneath  the 
tlexor  t«ndons.  From  the  latter  arch  are  given  off  eight  interosseous  branches, 
four  palmares  and  four  dorsales,  the  latter  passing  through  the  intermetacarpal 
spaces  and  anastomosing  with  branches  of  the  anterior  interosseous  artery. 
All  these  vessels  pass  down  the  digits,  and  join  ultimately  the  collateral 
palmars,  which  emanate  from  the  superficial  palmar  arch.  Thus  there  are 
three  sets  of  digital  vessels,  an  anterior,  and  a  superficial  and  deep  posterior. 

The  carotid  arteries  arise  singly  from  the  brachio-cephalic  trunk,  but  other- 
wise resemble  those  of  the  horse  ;  in  their  breaking  up  and  in  the  disposition. 
of  the  occipital  artery  and  ramus  anastomotiaus  there  is  no  important  deviation. 
The  internal  carotid  enters  the  carotid  canal,  passes  forwards,  and  csnds  a  pro- 
jecting loop  out  through  the  carotid  foramen,  receiving  a  small  branch  of  the 
external  carotid  ;  it  joins  the  spheno-spinal  and  recurrent  ophthalmic  branches, 
forming  a  kind  of  rudimentary  rete  mirabile. 

The  glasso-facial  artery  is  represented  by  separate  facial  and  lingual  branches. 

The  internal  maxillary  artery  resembles  that  of  the  horse  ;  the  superior 
dental  is  usually-  regarded  as  its  continuation.  It  gives  ofi"  an  alveolar  artery 
which  chiefly  supplies  the  orbital  gland. 

The  receptaculum  chyli  in  camivora  is  very  large,  extending  forwards  as  far 
as  the  thorax.  The  thoracic  duct  usually  bears  a  marked  resemblance  to  that 
of  the  hog. 

RODENTIA. 

Even  were  the  subject  of  importance,  there  is  little  space  for  iU  consideration 
here.  It  is,  however,  interesting  to  note  that  the  heart  presents  external  indica- 
tions of  division,  the  apsx  being  in  some  cases  slightly  cleft.  The  external 
jiigular  vein  is  very  much  larger  than  the  internal,  and  there  are  two  separate 
Anterior  vena3  cavae. 

AVES. 
The  heart  in  birds  is  divided  into  four  cavities  as  in  mammals  ;  its  apex  is 
situated  between  the  lobes  of  the  liver,  as  there  is  no  absolute  separation  be- 
tween the  thoracic  and  abdominal  cavities. 


CIRCULATION    IN    LOWER    ANIMALS. 


The  right  auricle  is  mucli  larger  than  the  left,  and  a  single  triangular 
"valve  takes  the  place  of  the  tricuspid. 

The  common  aorta  divides  into  three  branches,  a  singla  descending  or 
posterior  aorta,  and  a  right  and  left  trunk,  termed  by  Chauveau  the  bradhio- 
cephalic  arteries,  the  first  supplying  chiefly  the  viscera ;  the  latter  the  wing, 
head,  neck,  ai  d  anterior  parietes  of  the  body  ;  these  lateral  trunks  are  regarded 
by  some  authorities  as  representing  the  mammalian  thoracic  arteries,  giving  ofl" 
the  carotid  and  subclavian  branches. 

A  large  number  of  retia  mirabilia  are  found  among  the  arteries  of  the  head 
and  viscera. 

There  is  only  one  terminal  pulmonary  vein  and  two  superior  cavce.  The 
jugular  veins  have  a  large  transverse  anastomotic  branch  just  below  the  cranium. 
The  portal  vein  receives  branches  from  the  veins  of  the  posterior  extremities^ 
notably  the  coccygeo-mesenteric  vein,  which  is  con-  a 

nected  with  the  femoral  by  the  renal-portal  vein. 
Thus  is  constituted  the  renal-portal  system,  whose 
existence  in  the  bird  is  a  disputed  point,  even 
amongst  high  authorities. 

The  blood  of  birds  is  higher  in  temperature  than 
that  of  any  other  vertebrate  class.  The  corpuscles 
are  large,  elliptical  in  shape,  and  nucleated. 

The  lymphatics  consist  of  glands  and  vessels. 
There  are  two  thoracic  ducts,  each  discharging  into 
the  cava  of  its  own  side.  They  originate  in  a  kind 
of  receptaculum  chyli,  near  the  ccsliac  axis.  The 
glands  are  said  to  be  confined  to  the  cervical  region. 

CIRCULATION    IN    LOWER    ANIMALS. 

It  may  be  not  out  of  place  here  to  explain  very 
briefly  how  the  circulatory  apparatus,  in  animals 
placed  lower  than  the  class  Aves,  differs  in  the 
general  plan  from  the  type  we  have  hitherto  con- 
sidered. It  will  be  seen  that  in  none  of  the  mammals 
or  birds  we  have  attempted  to  describe,  is  there  any 
important  difference  in  the  general  plan  of  the  heart, 
course  of  the  blood,  or  function  of  the  vessels. 

In  that  class  placed  next  below  the  Aves,  the  Beptilia,  or  reptiles,  we  find 
the  following  interesting  features  (see  Fig.  171).  The  heart  is  less  complex, 
having  only  three  cavities,  two  auricles,  and  one  common  ventricle.  As  the 
general  disposition  of  the  vessels  is  the  same  as  in  the  heart  of  four  cavities,  it 
follows  that  both  the  purified  blood  from  the  lungs,  and  the  venous  blood  from 
the  cavae,  are  passed  through  their  respective  auricles  to  the  ventricle,  where  they 
become  mixed.  This  mixed  blood  is  driven  into  the  aorta  and  pulmonary  artery, 
both  of  which  arise  from  the  common  ventricle.  Hence,  though  the  circulation 
in  these  animals  is  double,  the  blood  supplied  to  the  tissues  is  impure  or  mixed. 

In  a  still  lower  class  of  animals,  that  of  the  Pisces,  or  fishes,  we  find  tkat  the 


Flo.  171. 
Diagram  of  the  Circu- 
lation in  a  Reptile,  a. 
Pulmonic,  and  6,  Soma- 
tic circulation  ;  c,  Heart, 
showing  the  three  cavi- 
ties. The  arrows  indicate 
the  course  of  the  blood 
current. 


464 


COMPAEATIVE    ANGIOLOGY. 


ieart  is  still  more  rudimentary,  consisting  of  but  two  cavities,  an  airricie  qjaj 
a  ventricle,  but  still  the  tissues  are  supplied  with  pure  arterial  blood  •  the 
course  of  the  blood  being  as  follows  : — The  venous  blood  is  conveyed  by  the 
cava  to  the  auricle,  thence  into  the  ventricle,  and  then  by  the  branchial  artery 
to  the  BranchicB  or  gills,  structures  which  are  analogous  to  the  lungs  of  higher 
animals,  and  in  which,  consequently,  the  blood  becomes  arterialised.  The 
blood  thus  purified,  is  sent  from  the  gills  throughout  the  body  to  supply  the 
various  tissues,  and  is  finally  returned  by  the  cava  to  the  heart.  Hdnce  the 
circulation  in  these  animals  is  single,  the  purified  blood  not  being  returned  to 
the  heart,  but  driven  all  through  the  body.  The  impulse  of  the  heart  is  there- 
fore branchial. 

In  the  higher  orders  of  the  Crustacea,  a  still  lower  class  of  animals  (Inverte- 


Fio.  172. 
Diagram  of  the  Circulation  in 
a,  Fish,  a,  Branchial  circulation  ; 
6,  Somatic  circulation  ;  c,  Heart ; 
d,  Auricle  ;  e,  Ventricle  :  /,  Arte- 
rial trunk. 


Fig.  173. 
Diagram  of  the  Circulation 
in  a  Crustacean,  a,  Brau- 
chial ;  h,  Somatic  circulation. 
On  the  right  is  the  heart  with 
its  single  cavity,  and  on  the 
left  the  venous  lacunae. 


"brate),  we  find  that  the  cavities  of  the  heart  are  reduced  to  one,  which  is 
Tiowever  contained  in  a  kind  of  sac,  very  incorrectly  called  the  pericardium. 
Although  these  animals  are  supplied  with  gills,  the  impulse  of  the  heart  is 
systemic,  not  branchial ;  and,  as  in  the  fishes,  the  circulation  is  single.  The 
Mood  is  driven  by  the  heart  through  the  body,  and  then  collected  into  certain 
venous  dilatations  or  lacunae,  whence  it  is  conveyed  to  the  branchiae  for 
■purification.  The  branchial  vesseb  then  pour  it  into  the  so-called  pericardium, 
and  it  finally  re-enters  the  heart  by  a  number  of  valvular  orifices. 

The  blood  thus  supplied  to  the  tissues  is,  however,  not  pure  ;  for  it  is  ascer- 
tained that  certain  veins,  instead  of  leading  to  the  lacunae,  or  branchiae,  pass 
to  the  pericardium,  ia  which  cavity  the  blood  thus  becomes  mixed. 


CHAPTER  VI 

NEUROLOGY. 

The  subject  of  this  chapter,  the  nervous  system,  includes  those 
organs  which  may  be  regarded  as  receiving  and  interpreting 
impressions ;  stimulating  and  regulating  the  vital  functions.  The 
nervous  system  in  the  broad  sense  consists  of  three  sets  of  organs, 
peripheral,  central,  and  communicating,  the  function  of  the  latter 
being  to  establish  a  communication  between  the  other  two ;  that 
of  the  first  to  receive  and  deliver  impressions  ;  and  that  of  the 
second  to  generate  the  nervous  force.  In  other  words,  the  system 
comprises  peripheral  end-organs,  nerves,  and  nerve  centres  ;  it  is 
with  the  two  latter  that  we  have  more  immediately  to  deal.  The 
nervous  system  is  divided  into  two  minor  systems — the  Cerebro- 
spinal, which  is  to  a  considerable  extent  influenced  by  the  will  of 
the  animal ;  and  the  Sympathetic,  or  ganglionic  system,  which 
comprises  the  nerves  of  organic  life,  which  are  not  directly  influ- 
enced by  the  will.  Each  of  these  has  its  own  central  and 
peripheral  organs. 

In  the  first,  the  centre  is  made  up  of  two  portions — one  large 
and  expanded,  the  brain  or  encephalon,  which  occupies  the  cranial 
cavity  ;  the  other,  the  spinal  cord,  is  elongated  and  continuous 
with  the  brain,  being  lodged  in  the  canal  of  the  vertebral  column. 
The  communicating  portion  of  this  system  consists  of  the  cerebro- 
spinal nerves,  which  leave  the  axis  in  symmetrical  pairs,  and  are 
distributed  to  the  voluntary  muscles,  and  the  organs  of  common 
sensation,  and  special  sense. 

In  the  second,  the  central  organ  consists  of  a  chain  of  ganglia 
connected  by  a  nerve  cord,  which  extends  from  the  head  to  the 
coccyx,  on  each  side  of  the  spine.  The  nerves  of  this  system  are 
distributed  to  the  involuntary  muscles,  mucous  membranes,  viscera, 
and  blood-vessels.  The  two  systems  have  free  intercommunica- 
tion, ganglia  being  placed  at  the  junctions. 

465  2  H 


466 


NEUROLOGY. 


NERVOUS    TISSUE. 


Two  substances,  distinguishable  by  their  colour,  enter  into  the= 
formation  of  nervous  tissue — viz.,  the  white  and  the  grey  matter.. 
Botb  are  soft,  fragile,  and  easily  injured,  in  consequence  of  which 
the  principal  nervous  centres  are  always  well  protected  by  th& 
skeleton.  When  examiced  under  the  microscope,  two  distinct 
structures,  fibres  and  cells,  are  found ;  the  fibres  being  of  two 
kinds,  the  white  or  medullated,  and  grey  or  non-medullated,  the 
former  being  more  abundant. 

The  white  fibres,  which  form  the  white  matter  of  the  brain, 
spinal  cord,  and  the  nerves,  and  are  also 
sparingly  met  with  in  the  ganglia  and 
nerves  of  the  sympathetic  system,  have 
th/ee  distinct  components — \st,  An  exter- 
nal envelope,  the  neurilemma,  which  is 
fine,  transparent,  and  nearly  homogeneous; 
2nd,  A  layer  of  white,  fatty  matter,  the 
medullary  sheath,  or  ivhite  substance  of 
Schwann  ;  and  Srd,  the  cylinder  axis,  or 
priniitive  band  of  Remak,  in  the  centre 
of  all.  The  diameter  of  these  fibres  varies 
between  TrWth  and  Wxnrth  of  an  inch, 
though  some  are  very  much  less. 

The  grey  or  non-medullated  fibres 
constitute  the  chief  nerves  of  the  gang- 
lionic system,  and  are  also  present  in  the 
They  are  smaller  than  the  white  fibres, 
resembling  their  cylinder  axis,  measuring  from  TtkVxrth  to 
ainnrth  of  an  inch  in  diameter,  and  are  apparently  almost 
homogeneous  in  their  structure. 

The  nerve  cells,  or  ganglionic  corpuscles,  are  found  in  the 
nerve  centres,  and  in  the  peripheral  end  organs  of  some  of  the 
nerves.  In  shape  they  are  spheroidal,  caudate,  or  stellate. 
Each  cell  is  composed  of  a  transparent  membrane,  filled  with  a 
homogeneous,  colourless  matrix,  in  which  is  a  number  of  diffused 
minute  granular  bodies,  and  an,  internal  vesicular  nucleus, 
presenting  one  or  more  minute,  but  distinct  nucleoli.  The 
processes  of  the  cells  become  continuous  with  the  cylinder  axes 
of  nerve  fibres,  while  the  medullary  sheath  appears  to  be 
prolonged  over  the  cell ;  hence  these  cells  have  been  described 


Werve   tissue 
and  fibres. 


Fig.  174. 

'bipolar    cells 


cerebro-spinal  nerves. 


NERVES. 


467 


as  "  nvxleated  enlargements  of  the  axial  cylinders."  The  cells 
are  termed  unipolar,  bipolar,  and  multipolar,  according  to  the 
number  of  processes  they  possess. 

The  ganglia  are  composed  of  nerve  cells  and  gelatinous  fibres, 
invested  by  a  thin  envelope,  continuous  with  the  neurilemma  of 
the  nerves,  which  sends  minute  processes  inwards. 


NERVES. 

A  nerve  consists  of  a  bundle  of  tubular  fibres,  held  together 
by  areolar  tissue,  enclosed  in  a  membranous  sheath,  and  divided 
into  a  number  of  fasciculi,  each  being  invested  by  an  inflection 
of  the  sheath ;  they  have  also  an  external 
covering  of  cellular  tissue,  known  as  the 
vagina  cellulosa  or  cellular  sheath. 

During  their  course,  the  nerves  have 
frequent  intercommunication,  either  by  con- 
necting branches  or  in  a  ,  more  intimate 
and  complex  manner  in  what  is  termed 
a  ^3?e5?us.  When  the  nerves  divide  into 
branches,  there  is  never  any  splitting  of 
the  ultimate  fibres,  nor  yet  is  there  ever 
any  coalescing  of  them — they  retain  their 
individuality  from  their  source  to  their 
termination.' 

Nerves  may  be  traced  from  the  surface  of 
the  brain  and  spinal  cord  into  the  substance 
of  these  organs,  the  place  where  they  leave  the 
surface  beiog  termed  the  apparent,  and  the 
ultimate  origin  the  deep  origin  or  root  of  the 
nerve.  In  some  cases  the  root  is  single,  but  in 
others  the  fibres  spring  from  different  parts  of 
the  nerve  centre  ;  such  nerves  are  said  to  have  two  or  more 
roots.  These  roots  may  have  different  functions,  as  in  the  spinal 
nerves,  where  the  superior  root  is  sensory  and  the  inferior  motor. 
Whenever  this  admixture  of  functionally  distinct  fibres  is  found, 
a  ganglion  is  placed  at  or  near  the  apparent  root  of  the  nerve. 

Nerves  terminate  in   a  variety  of  ways — by  loops,  as  in  the 
voluntary  muscles,  and  in  some  of  the  soft  structures,  as  the  dent^al 
pulp ;  by  terminal  plexuses,  and  bulbs  in  mucous  membranes, 
many  of  the  sensory  nerves,  there  are   small,  oval  masses, 
Pacinian  bodies,  at  or  near  their  peripheral  terminations ;   these 


Fig.  175. 

Pacinian  body  from  the 
mesentery  of  a  cat.  o, 
S  tern  of  the  body ;  b,  Layer 
of  connective  tissue ;  c. 
Cavity  of  the  body ;  d, 
Nerve  fibre. 


In 

the 


468  NEUROLOGY. 

are  plentiful  in  the  spinal  nerves.  Some  nerve  fibres  have  no 
termination,  but  form  a  loop  by  joining  with  others  in  the  same 
bundle,  and  so  return  to  the  axis  ;  while  others,  as  the  auditory 
and  optic  nerves,  have  end  organs  of  great  complexity. 

Nerves  which  convey  impressions  to  the  centres  are  termed 
centHpetal  or  afferent ;  those  which  transmit  stimuli  from  the 
centres  to  the  various  organs,  centrifugal  or  efferent ;  while 
those  which  pass  from  one  centre  to  another  are  called  inter - 
central. 

Centrifugal  nerves  are  called  motor  when  they  stimulate  mus- 
cular contraction,  and  if  this  contraction  be  in  the  coats  of  vessels, 
the  nerves  are  then  vaso-motor ;  when  they  stimulate  the  secre- 
tion of  glands,  they  are  called  secretory,  and  when  they  have  the 
power  of  diminishing  function, .  inhibitory ;  some  nerves  are 
believed  to  control  the  process  of  niftrition  in  the  parts  they 
supply,  and  have  been  named  trophic. 

Centripetal  nerves  which  convey  ordinary  feeling  are  termed 
sensory  ;  when  they  convey  impressions  peculiar  to  an  organ,  as 
the  nerves  of  sight  and  hearing,  they  are  known  as  nerves  of 
special  sense.  Nerves  conveying  impressions  which  lead  to  the 
stimulation  of  motor  nerves  are  termed  excito-motor  ;  if  to  that 
of  secretory  nerves,  excito -secretory ;  and  if  to  that  of  inhibitory 
nerves  excito-inhibitory.  This  reflection  of  nervous  impulse  from 
one  nerve  to  another  is  known  as  reflex  action. 


CEREBRO-SPINAL    SYSTEM. 

The  centre  of  this  system  is  the  cerebrospinal  axis,  consisting 
of  the  brain  and  spinal  cord,  which  like  their  coverings  or 
meninges,  are  continuous  with  each  other. 

The  cerebro-spinal  axis  is  invested  by  three  distinct  membranes 
— viz.,  the  dura  mater  externally,  the  arachnoid  in  the  middle, 
and  the  pia  mater  internally. 


MENINGES    OF   THE    SPINAL    CORD. 

The  dura  mater  of  the  cord  is  a  strong,  inelastic  membrane, 
composed  of  intersecting  bands  and  laminae  of  white  fibrous  tissue. 
It  extends  from  the  foramen  magnum,  to  which  it  is  attached,  and 
where  it  is  continuous  with  the  dura  mater  of  the  brai-D,  to  the 
posterior  extremity  of  the  neural  canal,  where,  as  a  slender  cord. 


MENINGES    OF    THE    BRAIN.  469 

it  blends  with  the  periosteum  in  the  first  bones  of  the  coccyx. 
Excepting  near  the  posterior  part,  where  they  are  attached  by 
£brous  slips,  the  dura  mater  is  separated  from  the  periosteum  of 
the  canal  by  areolar  tissue  and  a  plexus  of  veins,  so  that  it  forms 
a  loose  sheath  round  the  cord.  Its  inner  surface  is  smooth,  and 
lined  by  the  arachnoid  membrane  ;  opposite  each  intervertebral 
foramen  it  is  pierced  for  the  passage  of  the  spinal  nerves,  which 
it  accompanies,  as  a  tubular  sheath,  through  the  foramen. 

The  arachnoid  (so  called  from  its  extreme  tenuity,  resembling 
somewhat  a  spider's  web)  is  a  delicate  serous  membrane,  and,  like 
other,  serous  membranes,  is  a  shut  sac.  Its  visceral  layer  loosely 
envelops  the  pia  mater  of  the  cord,  leaving  between  them  an 
interval,  the  suh-arachnoidean  space,  continuous  with  an  opening 
at  the  posterior  border  of  the  brain,  which  contains  the  limpid 
cerebro-spinal  fluid.  The  parietal  layer  is  a  continuation  of  the 
visceral,  the  latter  surrounding  the  nerves  as  they  leave  the  cord 
until  they  pierce  the  dura  mater,  when  it  is  reflected  on  to  the 
inner  surface  of  that  membrane. 

The  pia  mater,  the  inner  envelope  of  the  cord,  is  a  thin  vascular 
membrane,  composed  of  areolar  tissue,  containing  blood-vessels. 
It  IS  less  vascular,  but  thicker,  denser,  and  more  fibrous  than  the 
corresponding  membrane  of  the  brain,  of  which  it  is  a  continua- 
tion. It  closely  invests  the  whole  surface  of  the  cord,  sends  pro- 
<!esses  into  its  longitudinal  fissures,  and  forms  a  sheath  for  the 
spinal  nerves.  When  the  cord  terminates,  the  pia  mater  is  pro- 
longed as  a  slender  filament  {filwm  terminale)  through  the 
centre  of  the  mass  of  nerves  forming  the  Cauda  equiiui,  and 
blends  with  the  terminal  coi'd  of  the  dura  mater. 

The  ligamentum  denticulatum  is  a  narrow  fibrous  band, 
which  runs  between  the  superior  and  inferior  roots  of  the  spinal 
nerves,  from  the  foramen  magnum  backwards,  so  as  to  form  a 
support  for  the  cord.  Its  inner  border  is  continuous  with  the 
pia  mater  ;  the  denticulations  of  its  outer  edge  being  attached  to 
the  dura  rx^ater  in  the  intervals  between  the  roots  of  the  nerves. 


MENINGES    OF    THE    BRAIN. 

The  Dura  mater  is  the  thick,  white,  fibrous  membrane  which 
lines  the  cavity  of  the  cranium,  acting  as  the  internal  periosteum 
of  the  bones.  It  is  continuous  with  the  spinal  dura  mater  at  the 
foramen  magnum,  and  is  also  prolonged  as  a  sheath  for  the  nerves. 


470  NEUROLOGY. 

In  some  places  its  layers  separate  to  form  irregular  channels,  the 
sinuses  of  the  dura  mater,  which  are  lined  by  a  continuation  of 
the  inner  coat  of  the  veins,  for  the  reception  of  the  venous 
blood.  On  its  external  surface,  the  branches  of  the  meningeal 
arteries  can  be  traced ;  and  from  the  inner  surface,  which  is 
smooth  and  lined  by  the  arachnoid  membrane,  processes  are 
directed  inwards  for  the  support  and  protection  of  the  different 
parts  of  the  brain.  These  membranous  processes,  regarded  as 
duplicatures  of  the  inner  layer  of  the' dura  mater,  are  three  in 
number — viz.,  the  falx  cerebri,  tentorium  cerebelli,  and  falx 
cerehelli. 

The  falx  cerebri,  so  named  in  the  human  subject  from  its 
being  sickle-shaped,  is  an  arched  process,  which  descends  in  the 
longitudinal  fissure  between  the  hemispheres  of  the  cerebrum. 
Anteriorly  it  is  attached  to  the  crista  galli  process,  and  posteriorly 
to  the  upper  part  of  the  ossific  tentorium.  Its  convex  upper 
border,  along  which  runs  the  superior  longitudinal  sinus,  is 
attached  along  the  longitudinal  auture  joining  the  pairs  of  parietal 
and  frontal  bones  ;  its  under  border  is  free. 

The  tentorium  cerebelli  is  a  transverse  partition,  formed  by 
lateral  inflections  of  the  dura  mater,  between  the  cerebellum  and 
the  hemispheres  of  the  cerebrum.  Each  lamina  presents  an  outer 
convex  adherent  border,  attached  to  the  lateral  ridges  of  the  ossific 
tentorium,  and  enclosing  a  lateral  sinus ;  an  inferior  concave,  free 
border,  turned  outwards  and  a  little  forward ;  a  superior  extremity 
attached  to  the  ossific  tentorium ;  and  an  inferior  extremity, 
which  reaches  the  upper  part  of  the  Gasserian  ganglion,  and 
contains  the  petrosal  sinus. 

The  falx  cerebelli  is  a  short  double  process,  proceeding  from 
the  ossific  tentorium  towards  the  foramen  magnum,  between  the 
lobes  of  the  cerebellum.  The  occipital  sinus  is  found  witliii* 
its  folds. 

The  Aeachnoid  membrane,  like  that  of  the  cord,  is  a  closed 
sac,  the  parietal  layer  of  which  is  firmly  adherent  to  the  dura 
mater,  and  is  reflected  over  the  several  processes.  The  visceral 
layer  is  thin  and  transparent  on  the  upper  surface  of  the  brain, 
to  which  it  is  loosely  attached  by  the  subarachnoidean  cellular 
tissue ;  at  the  base,  where  the  subarachnoidean  spaces  are  found, 
it  is  thicker  and  more  opaque.  These  spaces,  three  in  number 
(anterior,  middle,  and  posterior),  contain  the  cerebro-spinal  fluid ;. 
they  communicate  freely  with  each  other,  and  with  the  spinal 


SPINAL    CORD. 


471 


subarachnoidean  space.  The  anterior  space  is  situated  between 
the  lobes  of  the  cerebrum,  immediately  in  front  of  the  optic 
commissure  ;  the  middle,  between  the  pituitary  body  and  the 
pons  Varolii  ;  and  the  posterior,  between  the  medulla  oblongata 
and  the  posterior  part  of  the  cerebellum. 

Yellow  and  white  fibres,  intimately  blended,  enter  into  the 
composition  of  the  arachnoid,  the  free  surface  being  lined  with 
scaly  epithelium.  It  surrounds  the  nerves  at  their  apparent 
origin,  and  accompanies  them  to  their  exit  from  the  cranial 
cavity,  when  the  layers  become  continuous. 

The  PiA  MATER  (tunica  vasculosa)  is  closely  adherent  to  the 
entire  surface  of  the  brain,  dipping  into  every  fissure  or  depres- 
sion, into  the  sulci  between  the  convolutions,  and  passing  into 
the  interior  in  several  places.  It  is  thinner,  but  much  more 
vascular,  than  the  pia  mater  of  the  cord,  its  vascularity  being 
greatest  on  the  surface  of  the  hemispheres,  where  it  is  little  more 
than  a  ramification  of  minute  vessels,  part  of  which  can  be 
traced  some  distance  into- the  brain  substance. 


SHITAL    COED. 

The  spinal  cord,  medulla  spinalis,  or  myelon,  is  a  large,  white, 
irregularly  cylindrical  cord,  flattened  from  above  downwards, 
which  extends  from  the  foramen  magnum  to  the  sacral  portion  of 
the  neural  canal,  where  it  terminates  in  a  slender  filament.  In 
order  to  allow  considerable  motion  of  the  vertebral  column  with- 
out risk  of  injury  to  the  cord,  it  is  loosely  suspended  in  the  canal, 
the  other  contents  being  the  meninges  and  subarachnoid ean 
fluid,  with  numerous  arterial  and  venous  plexuses.  In  its  course, 
the  cord  varies  in  size,  being  dilated  at  its  origin,  where  it  joins 
the  medulla  oblongata,  and  having  a  considerable  enlargement 
between  the  fifth  cervical  and  second  dorsal  vertebrae,  where  the 
large  nerves  which -form  the  brachial  plexus  are  given  off;  and 
again  at  and  posterior  to  the  third  lumbar  vertebra,  where  the 
lumbar  and  sacral  nerves  which  constitute  the  lumbo-sacral 
plexus  arise.  Towards  its  termination  the  cord  gradually  tapers 
to  a  point,  to  which  portion  the  name  conus  medullaris  has  been 
applied  ;  and  here  is  given  off  an  indefinite  number  of  filaments  to 
supply  the  coccyx  and  neighbouring  structures,  forming  a  bundle 
of  nerves  termed  the  cauda  equina.  The  roots  of  the  spinal 
nerves  have  their  origin  opposite  to  the  intervertebral  foramina. 


472 


^■EUROLOGT. 


The  terminal  filament  of  the  cord,  which  is  constructed 'of  whit& 
fibrous  tissue  externally,  and  nervous  matter  internally,  passes 
through  the  centre  of  the  cauda  equina  backwards  to  the  second 
coccygeal  bone. 

When  denuded  of  its  coverings,  the  spinal  cord  is  found  to  be 
divided  into  tv.-o  lateral  symmetrical  columns  by  longitudinal 
fissures,  one  on  the  upper  surface,  narrower  but  deeper,  the 
superior  median  fissure;  the  other,  on  the  under  surface, 
broader,  but  shallov/er,  the  inferior  median  fissure.  A  layer  of 
white  matter  at  the  bottom  of  the  latter  fissure  unites  the  lateral 
columns,  constituting  the  inferior  white  commissure,  above 
which  a  band  of  grey  matter,  the  grey  commissure,  extends  th& 
whole  length  of  the  cord. 


Fio.  17e. 
Transverse  Section  through  Spinal  Ccrd,  showing  roots  of  nerve. 
o,  Inferior  median  fissure ;  B,  Superior  median  fissure ;  c,  Central 
canal ;  d,  Inferior,  and  e,  Superior  cornu  of  grey  matter  ;  g,  Inferior 
h,  middle,  i,  superior  columns  (?)  ;  fc,  White  commissure  ;  I,  Grey  com- 
missure ;  m,  Motor  root,  and  n,  Sensory  root  of  spinal  nerve ;  n'. 
Ganglion  on  sensory  root.    (This  cut  is  lettered  upside-down.) 

Each  lateral  column  is  again  divided  conventionally  into  three 
parts  by  lateral  fissures,  a  superior  (best  marked),  corresponding 
with  the  sensory,  and  an  inferior,  corresponding  with  the  motor 
roots  of  the  spinal  nerves. 

A  transverse  section  of  the  cord  shows  the  white  matter  exter- 
nally, in  the  form  of  two  semi-cylinders,  and  the  grey  matter  in 
the  centre  of  each.  The  grey  substance  varies  in  size  in  different 
parts  of  the  cord,  but  always  presents  the  same  general  appear- 
ance of  two  crescentic-shaped  masses  united  in  the  middle  by  the 
grey  commissure.  Each  crescent  presents  two  cornua  or  horns  ; 
the  superior,  long  and  thio,  traversing  the  whole  thickness  of  the 
cord,  and  prolonged  outwards  and  upwards  to  the  superior  lateral 
fissure  ;  the  inferior,  thicker  and  more  irregular,  is  directed  towards. 


MEDULLA    OBLONGATA.  473 

the  inferior  roots  of  the  nerves.  The  connective  tissue  of  the  cord 
is  a  reticular  variety,  very  delicate  and  gelatinous  in  its  structure  ; 
it  is  termed  the  neuroglia.  In  the  middle  of  the  grey  commis- 
sure the  central  spinal  canal  runs  the  whole  length  of  the  cord, 
being  continuous  anteriorly  with  the  fourth  ventricle  of  the 
brain. 

The  fibres  of  the  cord  are  not  all  continuous  with  those  of  the 
encephalon,  some  being  proper  to  the  cord  itself;  while  of  those 
which  proceed  to  the  brain,  some  decussate  with  each  other  before 
doing  so. 

The  proportionate  size  of  the  brain  and  spinal  cord  varies  in 
different  animals,  according  to  the  position  which  they  occupy  in 
the  scale  of  intelligence  ;  the  higher  that  position  the  larger  and 
heavier  proportionately  is  the  brain,  and  the  smaller  and  lighter  the 
cord  relatively.  Thus  in  man,  the  most  intelligent  of  the  animal 
creation,  the  brain  averages  50  oz.,  and  the  spinal  cord  about  1^ 
oz. — a  proportionate  weight  of  1  to  33.  In  the  horse  the  brain 
averages  about  23  oz.,  and  the  spinal  cord  10|  oz,,  or  a  propor- 
tionate weight  of  1  to  2*19. 


THE    ENCEPHALON, 

The  encephalon  or  brain  is  that  portion  of  the  cerebro-spinal 
axis  situated  within  the  cranium.  In  form  it  is  a  slightly  flattened 
and  elongated  ovoid  body,  which  may  be  considered  as  consisting 
of  four  parts — the  medulla  oblongata,  the  pons  VaroUi,  the 
cerebellum,  and  the  cerebrum. 


MEDULLA    OBLONGATA. 

This  is  the  prolongation  of  the  spinal  cord,  extending  to  the 
pons  Varolii,  from  which  it  is  separated  by  a  shallow  fissure. 
This  portion  of  the  brain  is  very  large  in  the  domesticated 
animals,  and  wherever  the  spinal  cord  is  largely  developed  It 
is  pyramidal  in  shape,  the  narrowest  part  being  continuous  with, 
the  cord.  The  inferior  surface  is  convex,  and  rests  upon  the 
basilar  process,  and  the  superior  surface  is  received  between  the 
hemispheres  of  the  cerebellum,  where  it  forms  the  floor  of  the 
fourth  ventricle.  Two  median  fissures,  continuous  with  the  supe- 
rior and  inferior  longitudinal  fissures  of  the  cord,  divide  the  medulla 
into  symmetrical  halves.     The  superior,  deep  and  narrow,  expands 


474 


NEUROLOGY. 


into  the  posterior  part  of  the  fourth  ventricle,  while  the  inferior 
terminates  in  a  small  depression,  the  foramen  ccecum,  at  the  pos- 
terior part  of  the  pons  Varolii.  On  each  half  of  the  medulla  the 
following  objects  can  be  distinguished — viz.,  the  inferior  pyra- 
mids, the  olivary  bodies,  the  restiform  bodies,  the  intermediate 
fasciculi,  and  the  superior  pyramids. 

The  inferior  pyramids  are  bundles  of  white  fibres,  placed  on 
each  side  of  the  inferior  median  fissure,  and  continuous  with  por- 
tions of  both  the  inferior  and  lateral  columns  of  the  cord.  They 
are  constructed  of  three  sets  of  fibres,  the  innermost  of  which 

decussate  with  those  of  the  oppo- 
site pyramid ;  the  second  pass 
in  a  direct  manner  from  the  cord; 
and  the  third,  the  arciform  fibres, 
form  a  series  of  curves  which 
wind  round  the  olivary  body,  to 
join  the  restiform  body. 

The  corpora  olivaria,  very 
rudimentary,  are  two  elongated, 
oval-shaped  bodies,  on  the  outside 
of  the  inferior  pyramids.  They 
are  separated  from  the  pons 
Varolii  by  a  slight  depression, 
and  are  partly  covered  by  the 
arciform  fibres.  A  section  shows 
the  corpus  olivarium  to  be  a  mass 
of  white  matter,  in  which  is  a 
hollow  indented  capsule  of  grey 
matter  {corpus  dentatum).  This 
capsule  has  an  anterior  opening, 
and  contains  a  nucleus  of  white 
matter,  from  which  a  bundle  of  fibres  springs.  These  fibres  pass 
through  the  opening,  and,  joining  the  fibres  from  the  inferior 
pyramids,  constitute  the  olivary  colurans,  which  become  con- 
tinuous with  the  thalami  optici  and  corpora  quadrigemiua. 

The  restiform  bodies  constitute  the  lateral,  and  greater  part 
of  the  superior- portion  of  the  medulla,  and  form  the  connecting 
link  between  the  cord  and  cerebellum.  They  are  composed 
chiefly  of  white  longitudinal  fibres,  derived  from  the  superior  and 
lateral  columns  of  the  cord,  and  the  arciform  fibres,  and  they 
increase  in  thickness  as  they  pass   forwards  and  upwards  to  form 


Fig.  177. 
Ease  of  the  brain,  a  a,  Crura  cerebri  ; 
i,  Corpus  albicans  ;  c,  Infundibulum  ;  d. 
Pituitary  body  ;  e,  Mammillary  eminence  ; 
/,  Tuber  cinertum.;  g,  Pons  VaroMi  ;  g'  g'. 
Middle  peduncles  of  the  cerebellum  ;  h. 
Medulla  oblongata ;  i  i,  Inferior  pyra- 
mids ;  k  k.  Olivary  bodies  ;  I  I,  Restiform 
bodies. 


CEEEBELLUM.  475 

the  posterior  peduncles  of  the  oerebellum  The  lateral  walls  of 
the  fourth  ventricle  are  formed  by  the  divergence  of  the  xestiform 
bodies. 

The  superior  pyramids  are  small  bands  of  fibrous  matter 
between  the  superior  mesian  fissure  and  restiform  bodies  on  each 
side.  They  are  a  continuation  of  the  superior  columns  of  the 
cord,  passing  to  the  crura  of  the  cerebrum. 

The  intermediate  fasciculi  are  bundles  of  fibres,  which  pass 
from  the"  lateral  columns  to  the  crura  cerebri,  between  the  resti- 
form bodies  and  olivary  fasciculi. 


PONS    VAEOLII, 

The  pons  Varolii  is  the  transverse  projection  on  the  base  of  the 
brain,  between  the  medulla  oblongata  and  the  crura  of  the  cere- 
brum ;  it  is  lodged  in  the  anterior  depression  on  the  basilar 
process  of  the  occipital  bone,  and  has  a  groove  for  the  basilar 
artery  along  its  middle  line.  It  consists  of  a  semicircular  band 
of  white  fibres,  which  stretch  as  a  bridge  from  one  side 'of  the 
cerebellum  to  the  other,  each  extremity  being  curved  upwards,  to 
form  the  thick  processes,  which  constitute  the  middle  peduncles 
of  the  cerebellum. 

CEREBELLUM. 

The  cerebellum,  or  lesser  brain,  is  lodged  in  the  posterior  part 
of  the  cranial  cavity,  immediately  above  the  medulla  oblongata, 
and,  in  the  domestic  animals,  behind  the  cerebrum,  from  which  it 
is  separated  by  the  tentorium  cerebelli.  It  is  globular  or  elliptical 
in  shape,  the  transverse  diameter  being  the  greater,  and  it  consists 
of  a  body  and  three  pairs  of  peduncles,  the  anterior  of  which  con- 
nect it  with  the  corpora  quadrigemina,  the  middle  with  the  pons 
Varolii,  and  the  posterior  with  the  restiform  bodies  of  the  mod  ilia 
oblongata. 

The  body  of  the  cerebellum  is  composed  of  grey  matter  exter- 
nally, and  white  in  the  centre.  Its  surface  presents  numerous 
fissures,  the  two  deepest  of  which  run  in  a  longitudinal  manner, 
so  as  to  divide  it  into  a  middle  and  two  lateral  lobes.  The  middle 
lobe  projects  beyond  the  lateral  ones,  and  winds  forwards,  being 
known  as  the  vermiform  process ;  to  its  anterior  extremity  a  thin 
plate  of  white  fibre,  the  valve  of  Vieussens,  is  attached,  and 
passes  forwards  to  unite  the  anterior  peduncles  of  the  cerebellum. 


476  NEUROLOGY. 

This  valve  covers  the  aqueduct  of  Sylvius,  and,  with  the  vermi- 
form process,  forms  the  roof  of  the  fourth  ventricle.  The- 
posterior  vermiform  process  is  not  so  well  marked.  The  smaller 
tissures,  or  sulci,  divide  the  cerebellum  into  numerous  lobules, 
which,  when  separated,  are  found  to  be  indented  with  numerous 
secondary  fissures.  Each  lobule  consists  of  a  periphery  of  grey 
matter,  and  a  ramification  of  white  fibres  from  the  centre,  so 
that  the  whole  organ  presents  an  arborescent  appearance  when 
cut  across,  an  appearance  which  has  gained  the  name  of  the  arbor 
vitce.  The  centre  of  the  cerebellum  contains  a  mass  of  white 
matter,  within  which  is  a  denticulated  capsule  of  grey  matter 
(corpus  dentatum),  similar  to  that  of  the  olivary  bodies,  from 
which  white  fibres  proceed  to  the  peduncles  and  to  the  valve  of 
Vieussens,  the  centre  white  mass  consisting  of  three  bundles  of 
fibres,  each  of  which  proceeds  to  a  separate  peduncle. 


FOURTH    VENTRICLE. 

The  fourth  ventricle  is  the  lozenge-shaped  space  between  the 
cerebellum  and  the  medulla,  its  roof  being  formed  by  the  vermi- 
form process  and  valve  of  Vieussens,  its  lateral  walls  by  the 
superior  pyramids,  restiform  bodies,  and  anterior  peduncles  of 
the  cerebellum,  and  its  floor  by  the  medulla  and  pons  Varolii ; 
the  testes  being  its  boundary  anteriorly,  and  the  restiform  bodies 
posteriorly.  A  fissure,  continuous  with  the  superior  median 
fissure  of  the  cord,  passes  along  the  floor  of  the  ventricle  into  the 
aqueduct  of  Sylvius,  which  is  a  canal  leading  into  the  third  ven- 
tricle ;  and  on  either  side  of  this  fissure  a  few  fibres,  which  join 
the  auditory  nerve,  unite  at  an  angle  somewhat  resembling  the 
barb  of  a  pen,  and  constitute  what  is  known  as  the  calamus 
scriptorius.  The  lining  membrane  of  this  ventricle  is  continuous 
with  that  of  the  others,  through  the  aqueduct  of  Sylvius,  and 
v/ith  the  subarachnoidean  space  ;  it  forms  a  small  fringe  known 
as  the  choroid  plexus  of  the  fourth  ventricle. 

CEREBRUM. 

The  cerebrum,  or  great  brain,  occupies  the  anterior  portion  of 
the  cranial  cavity.  It  is  ovoid  in  shape,  with  an  irregularly 
flattened  base,  and  consists  of  lateral  halves  or  hemispheres, 
separated  by  the  longitudinal  fissure,  in  which  the  falx  cerebri  is. 


BASE    OF    THE    BRAIN. 


47r 


lodged.  Anteriorly  to  the  optic  commissures,  this  fissure  reaches 
quite  to  the  base,  but  cm  the  superior  surface  it  is  interrupted 
by  a  broad  lamina  of  white  fibres,  the  corpus  callosum,  or  great 
commissure  of  the  hemispheres  ;  and,  at  the  upper  part  of  its 
•posterior  extremity,  it  is  crossed  by  a  species  of  bridge,  under 
which  the  venas  Galeni  pass  to  the  interior.  Deep,  irregular 
sutci  map  out  the  surface  of  the  hemispheres  into  numerous  con- 
volutions, the  number  of  which,  and  the  depth  of  the  sulci, 
indicate  the  range  of  intelligence  possessed  by  the  animal,  as  the 
grey  matter,  which  is  believed  to  be  the  seat  of  the  intellectual 
faculties,  is  found  on  the  surface  of  the  convolutions  and  on  the 
sides  and  bottom  of  the  sulci,  so 
that  the  deeper  and  more  numer- 
ous these  are,  the  greater  is  the 
amount  of  grey  matter  in  the  brain. 
In  the  domesticated  animals, 
each  hemisphere  is  divided  into 
an  anterior  and  a  greater  lobe, 
the  posterior  lobe  which  is  found 
in  man  being  wanting.  The 
anterior  lobe,  which  forms  the 
bulk  of  the  organ,  is  separated 
from  the  greater  lobe  by  the 
fissure  of  Sylvius,  not  very  dis- 
tinct in  the  lower  animals.  This 
fissure,  which  is  on  a  level  with 
the  optic  tracts,  and  contains  the 
middle  cerebral  artery,  divides 
into  two  branches,  one  going 
upwards  and  forwards,  the 
other  downwards  and  inwards. 
Between  the  bifurcations,  a  cluster  of  convolutions,  forming  the 
island  of  Reil  or  central  lobe,  converge  towards  the  median  line. 
These  convolutions,  from  their  being  concealed  in  the  fissure,  are 
also  called  the  covered  convolutions. 


Fig.  178. 
Superior  aspect  of  the  brain,  a,  Left,  and 
a',  Eight  cerebral  hemisphere  ;  a".  Anterior 
lobe ;  a'",  Greater  lobe  ;  6,  Corpus  cal 
losum  ;  c.  Opening  of  venae  Galeni  ;  d,. 
Vermiform  process  ;  d'  d",  Lateral  lobes  of 
cerebellum. 


BASE    OF    THE    BRAIN. 

At  the  base  of  the  brain  are  the  crura,  or  peduncles  of  the 
^rebrum,  two  large  bundles  which,  coramencing  in  front  of  the 
pons    Varolii,  proceed  forward   in    a   divergent   manner,   entering 


478  NEUROLOGY. 

the  under  part  of  eacli  hemisphere,  and  terminating  in  the  optic 
thalami  and  corpora  striata.  These  cruVa  consist  of  two  layers 
of  white  matter,  with  a  mass  of  grey  matter,  the  locus  niger, 
interposed.  Both  layers  are  longitudinal,  the  superficial  being 
continuous  with  the  inferior  pyramids,  and  the  deep  with  the 
lateral  and  superior  columns  of  the  medulla  and  olivary  fasciculi. 
They  are  covered  by  the  corpora  quadrigemina  and  optic  thalami, 
and  are  crossed  in  front  by  the  optic  tracts  and  first  portion  of 
the  optic  nerves.  These  nerves  proceed  forwards  and  inwards, 
and  decussate  in  the  median  line,  the  junction  being  termed  the 
optic  commissure.  The  lozenge-shaped  space  between  the  crura 
and  the  optic  tracts  is  the  interpeduncular  space,  in  which  we 
find  the  pituitary  body  or  gland  {hypophysis  cerebri),  the 
infundibulum,  the  corpus  albicans,  the  locus  perforatus  posticus, 
and  the  pons  Tarini. 

The  pituitary  body  or  gland,  is  a  small,  round,  reddish-grey, 
■vascular  body,  lodged  in  the  sella  turcica,  where  it  is  held  by  a 
fold  of  dura  mater ;  it  is  similar  in  structure  to  the  ductless 
glands,  and  in  the  foetus  it  contains  a  central  cavity,  which  com- 
municates, through  the  infundibulum,  with  the  third  ventricle. 

The  corpus  albicans  is  a  round  object,  white  externally  and 
grey  internally,  situated  behind  the  optic  commissure.  It  is 
connected  with  the  crura  or  bulb  of  the  fornix.  From  its  under 
surface  is  prolonged  the  infundibulum,  a  conical  process  of 
reddish  colour,  to  the  summit  of  which  the  pituitary  body  is 
attached.  The  funnel-shaped  cavity  in  this  process  communicates 
superiorly  with  the  third  ventricle  of  the  brain. 

The  remaining  space  between  the  corpus  albicans  and  the 
crura  of  the  cerebrum,  forming  part  of  the  floor  of  the  third 
ventricle,  is  the  locus  perforatus  posticus,  the  numerous  minute 
openings  in  which  are  for  the  passage  of  blood-vessels  to  the 
optic  thalami.  The  white  fibres  which  cross  this  space  from  one 
crus  to  the  other  form  the  pons  Tarini. 

On  each  side,  rather  to  the  front  of  the  optic  tracts,  and  near 
the  commencement  of  the  Sylvian  fissure,  is  a  triangular  space 
of  grey  matter,  the  locus  perforatus  anticus.  This  space,  like 
the  posterior  perforated  space,  is  pierced  for  the  passage  of 
blood-vessels  to  the  corpora  striata,  which  lie  immediately  above* 

The  tuber  cinereum,  a  spherical  mass,  connected  with  the 
corpus  striatum,  is  situated  immediately  before  the  optic  tract, 
and  behind  it  is  the  mammillary  eminence. 


CORPUS   CAI.L03OL  479^ 

The  olfactory  bulbs,  the  apparent  origin  of  the  first  pair  of 
cranial  ne'rves,  arise  from  the  anterior  porfo:"ated  spaces.  They 
consist  of  a  layer  of  white,  surrounding  an  inner  tube  of  grey 
matter,  the  interior  being  hollow,  and  communicating  with  the 
lateral  ventricles. 

CORPUS   CALLOSUM. 

On  removing  the  upper  part  of  the  hemispheres,  by  a  section: 
midway  between  the  corpus  callosum  and  the  superior  surface  of 
the  brain,  a  central  mass  of  white  matter,  surrounded  by  a 
convoluted  border  of  grey,  is  exposed.  The  white  portion, 
known  as  the  centrum  ovale  Tninus,  is  studded  with  numerous 
red  spots,  yuncta  vasculosa;  caused  by  the  escape  of  blood  from, 
the  vessels  which  have  been  divided.  A  second  section,  made 
immediately  abov^e  the  corpus  callosum,  exposes  the  greatest, 
amount  of  white  matter,  centruTn  ovale  majus,  above  which,  oa 
the  inner  surface  of  the  hemisphere,  is  the  gyrus  fornicatus,  a 
convolution  whicb  follows  the  curve  of  the  corpus  callosum.  The 
space  between  this  convolution  and  the  corpus  is  known  as  thfr 
ventricle  of  the  corpus  callosum. 

The  corpus  callosum,  or  great  commissure  {trabs  cerebri),  is. 
th(;  white,  quadrilateral,  and  arched,  body  which  unites  the  hemi- 
spheres. Its  lateral  borders  are  liidden  by  the  gyri  fornicati  and 
substance  of  the  hemispheres,  in  which  they  become  lost ;  while 
the  middle  of  its  superior  surface,  seen  at  the  bottom  of  the 
longitudinal  fissure,  is  free,  and  covered  with  pia  mater.  Along- 
its  middle  line,  between  two  delicate  cords  of  white  matter  {strice 
longitudinales)  runs  a  line  or  seam,  the  raphe,  on  either  side  of 
which  may  be  seen  the  transverse  markings,  which  indicate  the 
direction  of  the  fibres  of  which  the  corpus  callosum  is  composed. 
Its  inferior  surface  is  connected  posteriorly  with  the  fornix,  the 
remainder  being  divided  by  the  septum  lucidum  into  two  parts, 
which  form  the  roofs  of  the  lateral  ventricles.  Its  anterior 
extremity  is  reflected  downwards,  the  bend  being  the  knee  or 
genu,  and  the  tapering  reflection  the  rostrum  or  beak.  From 
the  sides  of  the  rostrum  a  delicate  grey  membrane,  the  lamina 
cinerea,  extends  to  the  tuber  cinereum,  and  from  the  point 
divergent  white  bands,  the  crura  of  the  corpus,  extend  to  the 
anterior  perforated  spaces.  The  posterior  extremity  of  the 
corpus  callosum  is  thick,  and  forms  a  free  rounded  border,  which 
is  in  connection  with  the  fornix. 


480  NEUROLOOr. 


LATERAL    VENTRICLES. 


When  the  corpus  callosum  is  cut  through,  two  large  cavities  in 
the  substance  of  the  hemispheres,  the  lateral  ventricles,  are 
exposed.  These  cavities  are  lined  with  a  delicate  membrane, 
covered  with  ciliated  epithelium,  which  secretes  a  serous  liquid 
similar  to  the  spinal  fluid.  They  are  each  possessed  of  a  roof 
and  two  small  recesses  or  comua.  The  roof  of  the  body  of  the 
ventricle  is  formed  by  the  corpus  callosum,  and  the  Jioor  by  the 
corpus  striatum  in  front,  and  the  internal  part  of  the  hippo- 
campus behind ;  while  the  septum  lucidiim  stretches  as  a 
partition  between  the  two  ventricles.  Running  obliquely  from 
behind  forwards,  and  from  without  inwards,  between  the  corpus , 
striatum  and  the  hippocampus,  is  a  furrow  in  which  a  red 
vascular  fringe,  the  choroid  plexus,  is  lodged  ;  and  between  the 
corpus  striatum  and  the  thalamus  opticus  is  a  narrow  band  of 
white  matter,  the  taenia  semicircularis. 

The  anterior  cornu  stretches  from  the  body  of  the  ventricle 
into  the  anterior  lobe  of  the  cerebrum,  and  is  continued  as  a 
straight  canal  to  the  cavity  of  the  olfactory  lobe.  The  descend- 
ing cornu  passes  backwards,  outwards,  and  downwards,  and 
then  forwards  and  inwards,  thus  winding  round  the  optic 
thalamus  and  crus  cerebri,  to  terminate  in  a  cul-de-sac  in  the 
great  lobe,  near  the  fissure  of  Sylvius.  As  there  are  no  posterior 
lobes  to  the  cerebrum  of  quadrupeds,  so  the  posterior  cornu  of 
the  lateral  ventricle,  which  is  found  in  man,  is  also  wanting. 

The  septum  lucidum  is  the  thin,  semi-transparent  substance 
which  stretches  between  the  corpus  callosum  above  and  the  fornix 
below,  and  forms  the  partition  between  the  lateral  ventricles. 
It  is  triangular  in  shape,  and  in  man  is  said  to  be  composed  of 
two  laminae,  between  which  a  perfectly  isolated  cavity,  lined 
with  epithelium  and  containing  a  serous  fluid,  is  found.  This ' 
cavity  is  the  fifth  ventricle,  or  ventricle  of  the  septum  lucidum  ; 
it  appears  to  be  wanting  in  the  domesticated  animals. 

The  fornix  is  the  longitudinal  band  which  extends  as  an 
arch  along  the  lower  border  of  the  septum  lucidum,  and  is 
attached  to  the  posterior  extremity  of  the  corpus  callosum.  It  is 
made  up  chiefly  of  white  matter,  and  consists  of  a  body  and  four 
pillars.  The  body  is  triangular  in  form,  broad  and  flat  behind, 
and  narrow  in  front,  where  it  dips  down  to  leave  the  corpus 
callosum ;   its  edges  reach  the  choroid  plexuses,  and  its  inferior 


LATERAL    VENTRICLES. 


481 


surface  rests  on  the  velum  interpositum.  The  anterior  pillars 
descend  in  front  of  the  anterior  commissure  of  the  brain,  and, 
becoming  inflected  downwards  and  backwards  by  the  sides  of  the 
third  ventricle,  pass  to  the  corpus  albicans,  of  which  they  form 
the  external  fibres. 

Behind  the  anterior  pillars  of  the  foraiz  oa  each  side,  small 
openings  pass  downwards  and  backwards,  aui,  imiting  in  the 
middle  line,  lead  into  the  third  ventricle.  This  is  the  anterior 
common  opening  or  foramen  of  Monro,  which  forms  a  communi- 
cation between  the  two  lateral  and  the  third  veutrieles. 

The  posterior  pillars  of  the 
fornix  pass  downwards  and  ou""- 
wards  to  the  descending  comua 
of  the  lateral  ventricles,  and 
then  become  continuous  with  the 
hipppcampi.  The  thin  pro- 
longation behind  the  choroid 
plexus  is  the  corpus  fimhria- 
tum  (tcsnia  hip>pocam]n),  and 
the  transverse  white  fibres  which 
pass,  like  the  strings  of  a  harp, 
between  the  pillars,  form  the 
lyra. 

The  hippocampus  (coi'mu 
Aonmonis)  is  the  large  eminence, 
constructed  of  white  matter  exter- 
nally and  grey  internally,  which 
occupies  the  posterior  part  of 
the  floor  of  the  lateral  ventricle. 
The  liippocampi  are  continuous 
with  the  posterior  pdlars  of  the 
fornix,  and  are  separated  from  the  optic  thalami  by  the  choroid 
plexuses.  Posteriorly  they  diverge  and  enter  the  descending 
comua  of  the  ventricles,  occupying  the  cul-cU-sacs.  Towards 
their  terminations  they  become  enlarged,  and  each  presents  a 
number  of  rounded  elevations,  with  indented  edges  somewhat 
resembling  the  foot  of  an  animal,  and  called  the  pes  hippocampi. 
The  external  white  matter  of  the  hippocampi  is  continuous, 
through  the  corpora  fimbriata;  with  the  fornix  and  corpus 
callosLim. 

The  coi'pus  striatum  is  the  pear-shaped  prominence  which 

2i 


Fig.  179. 
Lateral  ventricles  opecod  from  ab<i7e.  X, 
Grey  matter ;  2,  WHilte  matter ;  a,  Soptaia 
lucidum ;  6,  Part  of  cori^us  callostiin ;  • », 
Hippocampus ;  d,  Tsenia  semicircularis ;  e, 
Clioro.J  plexus  ;  //,  Corpus  striatum  ;  g,  Aa- 
terior  cornu  of  the  ventricle  ;  h,  Furrow  leai- 
ing  backwards  to  descending  cornu. 


482  NEUROLOGY, 

occupies  tbe  anterior  region  of  the  floor  of  the  lateral  ventricle. 
Its  broad  anterior  extremity  stretches  into  the  anterior  comu, 
while  its  narrow  posterior  extremity  passes  into  the  descending 
cornu,  and  is  embedded  in  the  substance  of  the  hemisphere.  The 
furrow  along  its  oblique  inner  side,  which  separates  it  from  the 
hippocampus  and  the  optic  thalamus,  contains  the  choroid  plexus 
and  the  taenia  semicircularis.  The  corpora  striata  are  grey 
externally,  and  are  composed  of  grey  matter,  with  numerous 
white  fibres  traversing  it,  which  give  it  a  striated  appearance 
when  cut  across.      They  are  the  anterior  ganglia  of  the  cerebrum. 

The  tcenia  semicircularis  is  a  narrow,  white,  semi-transparent 
band,  which  separates  the  corpus  striatum  from  the  optic 
thalamus.  In  front  it  is  continuous  with  the  fornix,  becoming 
lost  near  the  foramen  of  Monro  ;  and  posteriorly  it  disappears  in 
the  descending  cornu.  A  vein  beneath  this  band  (vena  corporis 
striati)  receives  the  blood  from  the  corpus  striatum,. and  empties 
itself  into  the  vena  Galeni. 

The  velum  interpositum  is  a  double  fold  of  pia  mater,  which 
passes  into  the  anterior  of  the  brain  by  the  transverse  fissure, 
passing  between  the  corpora  quadrigemina  and  the  posterior  part 
of  the  corpus  callosum  ;  it  supports  the  fornix,  being  interposed 
between  that  body  and  the  third  ventricle.  It  is  triangular  in 
shape,  its  apex  corresponding  to  the  anterior  common  opening  ; 
it  consists  of  a  layer  derived  from  the  posterior  surface  of  the 
cerebrum,  and  another  from  the  anterior  surface  of  the  cere- 
bellum, A  process  from  it  embraces  the  pineal  gland;  and  its 
sides,  projecting  into  the  lateral  ventricles,  form  the  free  borders 
of  the  choroid  plexuses. 

The  choroid  plexus  is  the  vascular  fringe  in  the  lateral 
ventricle,  which  stretches  from  the  foramen  of  Monro  to  the 
descending  cornu,  in  the  furrow  between  the  hippocampus  and  the 
corpus  striatum.  It  is  a  highly  vascular  membrane,  containing- 
looped  plexuses  of  blood-vessels,  and  often  calcareous  matter. 
The  two  plexuses  are  united  by  a  cord  which  passes  through  the 
foramen  of  Monro. 

The  optic  thalami  (beds  of  the  optic  nerves)  are  the  two  large 
oval  bodies,  seen  when  the  fornix  and  hippocampi  are  removed, 
embracing  the  anterior  portion  of  the  crura  cerebri,  and  placed 
in  front  of  the  corpora  quadrigemina.  They  form  the  inferior 
ganglia  of  the  brain,  and,  like  the  corpora  striata,  consist  of  grey 
matter,   with  intersecting  white  fibres,   derived  from    the   crura 


THIRD   VENTRICLE. 


483 


cerebri  and  hemispheres.  The  anterior  portions  of  the  optic 
thaJami  approximate  most  closely.  Their  upper  surfaces  are 
convex  and  free,  and  their  posterior  surfaces  project  into  the 
descending  cornua.  of  the  lateral  ventricles.  Between  the 
thalami  and  the  crura  cerebri  are  rounded  grey  prominences,  the 
corpora  geniculata,  two  on  each  side,  the  innermost  of  which 
connect  the  thalami  with  the  nates, 
and  the  outermost,,  which  are  the 
larger,  with  the  testes. 


fir. 


THIRD    VENTRICLE. 


The  third  ventricle  is  the  space 
between  the  optic  thalami,  which  form 
its  lateral  walls,  seen  on  removing  the 
fornix  and  velum  interpositum,  which 
form  its  roof;  its  floor  being  formed 
by  the  tuber  cinereum,  c^irpus  albicans, 
locus  perforatus  posticus,  and  lamina 
cinerea;  its  anterior  boundary  is 
known  as  the  lamina  terminalis.  Three 
cwnmissures,  anterior,  middle,  and 
posterior,  cross  this  ventricle.  The 
anterior  is  a  bundle  of  white  fibres, 
which  forms  the  anterior  boundary  of 
the  ventricle,  and  unites  the  corpbra 
striata  behind  the  pillars  of  the  fornix  ; 
the  middle,  consisting  of  grey  matter, 

is  the  grey  or  soft  COm'misSV.re,  which      Fourth   ventricle;    +,  Aqueduct   of 

stretches  between  the  thalami;    and    syivius;  w  olfactory  lobes;  j- at.. 

'  Foramen  of  Monro;  i.f..  Lamina  ter- 

the  posterior,  which  is  white,  and  also    nunaiis ;  c.s.,  corpus  striatum ;  tk., 

•a        J.T.       xT.    1         •  xT-  J.  Optic  thalamus;   Pn.,  Pineal  gland; 

umtes  the  tnalami,  crosses  tne  poste-  Af.6.,  Middle  brain ;  ct.,  cerebellum.; 
rior  part  of  the  ventricle  in  front  of    ^■^-  Medulla  oblongata,  origins  of 

*,  1  mi  1  nerves:— /.,  Olfactory ;//.,  Optic. 

the  pmeaj    gland.      There  are   three 

openings  into  this  ventricle — 1st,  Between  the  anterior  and 
middle  commissure,  in  the  centre  of  the  floor,  a  deep  pit  or 
cavity,  the  iter  ad  infwndibulum-,  leads  to  the  infiindibulum ; 
2nd,  Between  the  grey  commissure  and  summit  of  the  fornix, 
the  foramen  of  Monro  leads  into  the  lateral  ventricles ;  and  Srd, 
The  aqueduct  of  Sylvius,  or  iter  e  tertio  ad  quartum  verutricu- 
lum,  which  leads   into   the   fourth   ventricle.       Through   these 


Fig.  180. 

Horizontal  and  diagramatic  section, 

showing  the  cavities   of   the   brain. 

1,    Olfactory    ventricle;     2,    Lateral 

ventricle;     3,    Third    ventricle;     4, 


484 


NEUROLOGY. 


openings,  the  lining   membrane   of  the  third  ^''entricle   is   con- 
tinuous with  that  of  the  others. 

The  phieal  gland  is  a  small  reddish-brown  tubercle,  placed 
behind  and  above  the  third  ventricle,  in  a  groove  between  the 
corpora  quadrigeraina,  where  it  is  kept  in  its  place  by  a  layer  of 
the  velum  interposittfm,  to  which  it  is  attached.  In  shape  it  is 
somewhat  conical,  having  a  broad  base  and  a  free  apex.  The 
base,  which  is  turned  forwards,  has  bands  of  white  matter,  its 

crura  or  peduncles,  passing  from 
it  to  the  optic  thaiami,  which 
they  join.  The  pineal  gland  is 
very  vascular,  and  is  constructed 
of  areolar  tissue  and  cells,  which 
contain,  besides  a  viscid  fluid,  a 
quantity  of  sand-like  matter  (acer- 
vulus  cerebri),  which  gives  a 
gritty  feel  to  the  body.  Though 
these  grains  often  accumulate 
largely  in  old  animals,  they  are 
not  regarded  as  the  products  of 
disease.  The  use  of  this  gland  is 
not  known;  the  ancients  regarded 
it  as  the  seat  of  the  soul,  and  the 
chief  source  of  nervous  power. 

The  corpora  qvAdrigemina  or 
optic  lobes  are  the  four  rounded 
eminences  situated  immediately 
behind  the  optic  thal'ami,  sur- 
mounting the  posterior  part  of 
the  crura  cerebri,  and  forming 
part  of  the  roof  of  the  aqueduct 
of  Sylvius.  They  are  separated 
by  a  crucial  depression,  and  are  placed  one  before  the  other  in  the 
median  line.  In  the  horse"  the  anterior  pair,  the  Tiates,  which  are 
grey  in  colour,  are  larger  than  the  posterior  pair,  the  testes,  which 
are  rounded  and  farther  apart.  These  bodies  have  coimectioa 
with  the  olivary  fasciculus,  and,  by  the  crura  cerebelli  ad  corpora 
quadrigemina,  oranterior  peduncles,  are  joined  to  the  cerebelhun. 
The  white  processes  (brachia),  given  off  from  each  side,  pass  to 
the  optic  thaiami  and  to  the  commencement  of  the  optic  tracts. 
The  corpora  quadrigemina  are  ganglionic  in  structure,  with  inters 


I    ■    J 

Fig.  181. 
Entire  brain  opened  from  above^the  fornix 
and  hippocampi  being  partly  removed,  a  a. 
Corpus  striatiun ;  b,  Body  of  fornix  :  c  c,  Tsenise 
semicireulares  ;  d  d,  Optic  thaiami ;  e,  Pineal 
gland ;  /,  Iter  ad  infundibulum ;  g,  Opening 
of  aqueduct  cf  Sylvius  ;  h  h,  Nates  ;  i  i,  Testes ; 
fc  k.  Anterior  peduncles  of  the  cerebellum ; 
k'  k',  Posterior  peduncles  of  the  cerebellum ; 
I,  Valve  of  Vieussens ;  m  m',  Cerebellum ;  n, 
Fourth  ventricle ;  o,  Calamus  scriptorius. 


ENCEPHALIC    CIRCULATION. 


485 


lacing  white  iibres,  the  testes,  in   addition,  having  an  escternal 
white  tunic. 

The  brain  is  developed  from  three  cerebral  vesicles,  the 
cavities  in  which  relatively  represent  the  third  and  fourth 
ventricles  and  the  aqueduct  of  Sylvius  ;  hence  these  three 
spaces  and  their  surroundings  may  be  said  to  constitute  the 
primary  division  of  the  brain,  and  the  parts  have  been  named 
respectively  the  fore,  the  middle,  and  the  hind  brain.  The 
lateral  ventricles  and  hemispheres  are  regarded  as  oflfshoots  or 
expansions  of  the  fore- brain. 


Fig.  1£2. 

Longitudinal,  vertical,  and  diagramatic  section  of  a  brain.  Hmp.,  Cerebral 
hemispheres;  Py.,  Pituitary  body;  Tli.E.,  Thalamencephalon,  or  fore-brain 
(the  dark  line  joining  Pn.  and  Py.  represents  the  lamina  terminalis) ;  C.Q., 
Corpora  quadrigemina  ;  C.C.,  Crura  cerebri ;  P.V.,  Pons  VaroUi.  The  origins 
of  the  twelve  cranial  nerves  are  marked  in  order,-  in  roman  figtires.  For 
other  descriptions,  see  explanation  of  Fig.  180. 


ENCEPHALIC   CIRCULATION. 

The  circulation  of  the  blood  in  the  brain  differs  in  a  remark- 
able degree  from  that  of  any  other  region,  one  great  peculiarity 
being  that  the  general  arrangement  of  the  vessels  in,  the  substance 
of  the  organ  is  almost  entirely  capillary.  The  larger  arteries  all 
ramify  in  the  dura  mater,  and  in  the  sulci  between  the  convolu- 
tions, and  the  smaller  branches,  from  which  the  extremely  fine 
penetrating  twigs  are  given  off,  in  the  pia  mater.  The  veins 
also  are  extremely  small,  and  as  a  rule  do  not  unite  to  form 
trunks  until  they  emerge  from  the  nervous  substance,  while  their 
superficial  branches,  dispersed  over  the  surface  of  the  brain,  enter 
large  sinuses  or  canals  within  the  dura  mater.  These  sinuses 
are  remarkable  for  their  rigidity,  which  enables  them  to  preserve 
an  almost  uniform  diameter.  Another  remarkable  feature  is  the 
great  freedom  of  anastomosis  which  exists  among  the  arteries,  in. 
the  larger  trunks,  as  well  as  in  the  smaller  branches. 


486 


NEUROLOGY. 


AETERIAL    CIRCULATION. 

Four  large  arteries,  two  internal  carotids,  and  two  cerebro- 
spinal branches  of  the  occipital  arteries,  convey  the  blood  to  the 
encephalon.  An  examination  of  the  tortuous  course  of  these 
arteries  shows  how  beautifully  Nature  l^as  provided  against  injury 
to  the  delicate  brain-structure,  by  the  blood  impinging  with  too 
great  a  force  against  its  base. 

The  Cerebro-SPINAL  arteries  enter  the  neural  canal  through 
the  internal  foramina  in  the  wings  of  the  atlas,  and  wind  round 
the  cord  to  its  inferior  surface,  where  they  each  divide  into  two 
branches,  one  of  which,  the  anterior  or  cerebral  branch,  passes 
forwards  and  joins  its  fellow  near   the   middle  of  the  medulla 

oblongata,  to  form  the  ba^ 
lar  artery.  The  posterior 
branches  pass  backwards,^ 
and  also  coalesce  to  form 
the  TniddZe  spinal  artery, 
which  runs  along  the  longi- 
tudinal fissure  of  the  cord. 
The  Basilar  artery  is 
continued  forwards  in  the 
longitudinal  furrow  on  the 
inferior  surface  of  the  pons 
Varolii,  near  the  anterior 
border  of  which  it  divides 
into  two  branches,  the  pos- 
terior cerebrals.  In  its  course  the  basilar  artery  gives  off — 1st, 
Several  small  branches,  which  penetrate  the  surface  of  the  medulla 
oblongata  and  pons  Varolii ;  2nd,  The  posterior  cerebellar s,  right 
and  left,  which,  like  the  terminal  branches,  are  given  off  at  right 
angles  behind  the  posterior  border  of  the  pons.  They  are  carried 
outwards,  ascending  over  the  pons,  and  then,  inflected  backwards, 
are  distributed  over  the  lateral  and  posterior  parts  of  the  cere- 
bellum. Zrd,  The  anterior  cerebellar  arteries,  two  or  three  on 
each  side,  the  principal  being  given  off  just  in  front  of  the  pons, 
on  the  outer  side  of  which  it  ascends  in  an  outward  and  slightly 
backward  direction,  to  be  distributed  to  the  anterior  surface  of 
the  cerebellum. 

The  terminal  branches,  the  Posterior  cerebral  arteries,  are 
the  largest,  and  form  the  posterior  border  of  that  peculiar  arterial 


Fig.  183. 
The  encephalic  arteries,  a,  Anterior  branch  of  the 
right,  and  a',  of  the  left  carotid  arteries  ;  6  6',  Posterior 
communicating  branches ;  c,  Inosculation  of  the  an- 
terior branches ;  d  d.  Inosculation  of  posterior  com- 
municating, and  posterior  cerebral  branches  of  basilar 
artery ;  e.  Basilar  trunk. 


ARTERIAL   CIRCULATION. 


487 


•circle  at  the  base  of  the  brain,  known  as  the  Circle  of  Willis. 
They  are  joined  by  the  posterior  communicating  branches  of.  the 
internal  carotid,  and  pass  outwards  round  the  crura  cerebri 
towards  the  transverse  fissure,  anastomosing  with  the  middle 
<;erebrals,  and  are  finally  distributed  over  the  posterior  part  of 
the  cerebrum.  In  their  course,  these  arteries  give  off  branches 
which  penetrate  the  interpeduncular  space,  and  a  branch  dis- 
tributed over  the  velum  interpo- 
situm. 

The  Internal  carotid  artery 
is  one  of  the  three  terminal 
Isranches  of  the  common  carotid. 
It  enters  the  cranial  cavity 
through  the  foramen  lacerum 
basis  cranii,  and  through  the 
cavernous  sinus,  where  it  forms  a 
double  curve.  The  first  of  these 
curves,  which  occupies  the  carotid 
fossa  in  the  sphenoid  bone,  has 
its  convexity  looking  forwards, 
and  the  second  has  its  convexity 
looking  backwards,  so  that  the 
two  curves  resemble  the  letter  S. 
After  the  second  curve,  a  trans- 
verse branch  joins  the  right  and 
left  trunks,  and  then  the  internal 
carotid  pierces  the  dura  mater, 
and,  at  the  fissure  of  Sylvius, 
divides  into  posterior  communi- 
cating and  a  branch  which  fur- 
nishes the  anterior  and  middle 
cerebral  arteries. 

The  Posterior  communica- 
ting  artery,  which  forms  the 

lateral  boundary  of  the  circle  of  Willis,  passes  backwards  by  the 
side  of  the  interpeduncular  space,  and  inosculates  with  the  pos- 
terior cerebral  branch  of  the  basilar  artery. 

The  Anterior  cerebral  branches  are  carried  forwards  to  the 
longitudinal  fissure,  where  they  converge  and  unite  ;  and,  passing 
through  the  fissure,  after  a  short  course,  the  vessel  divides  into 
two  branches,  which  subdivide  to  supply  the  corpus  callosum,  the 


FiQ.  184. 
Arteries  at  the  base  of  the  brain,  a,  Internal 
carotid ;  a',  Its  superior  ;  a",  Its  inferior 
branch  ;  6,  Jliddle  cerebral ;  b',  Artery  of  the 
choroid  plexiis ;  c,  Transverse  communicating ; 
d,  Anterior  cerebral ;  e  e,  Anterior  meningeal ; 
./.Branch  anastomosing  with  meningeal  branch 
of  ophthalmic  ;  g  g,  Basilar  ;  g'  g',  Posterior 
cerebrals  ;  h  h,  Cerebro-spinals  ;  i.  Middle 
spinal ;  k,  Arteries  of  the  medulla ;  I  I,  Pos- 
terior  cerebellar ;  m,  Artery  of  internal  ear : 
n.  Anterior  cerebellar;  o.  Artery  supplying 
optic  thalamus,  corpora  qnadrigetnina  and 
choroid  plexus. 


488  NEUROLOGY. 

third  ventricle,  and  the  under  surface  of  the  cerebrum.  Some- 
times, instead  of  forming  a  single  trunk,  the  anterior  cerebral 
arteries  are  joined  by  a  transverse  branch,  termed  the  anterior 
communicating  aHery.  These  vessels,  or  they  and  their  com- 
municating branch,  form  the  ant ero- lateral  and  anterior  boundaries- 
of.  the  circle  of  Willis. 

The  Middle  cerebral  artery  passes  directly  outwards  to  the 
fissure  of  Sylvius,  where  it  divides  into  numerous  branches,  which 
ramify  over  the  lateral  and  inferior  surfaces  of  the  cerebrum,  and 
anastomose  with  branches  of  the  anterior  and  posterior  cerebrals. 
Just  before  this  artery  divides,  it  gives  off  a  small  branch,  the 
anterior  choroid,  which  enters  the  descending  cornu  of  the  lateral 
ventricle,  and  supplies  the  choroid  plexus. 

venous  circulation. 

The  encephalic  venous  circulation  consists  of  veins  and  vascular 
triangular  channels  of  various  sizes,  found  within  the  dura  mater. 
These  are  the  venous  sinuses,  which  are  lined  by  a  continuation 
of  the  inner  tunic  of  the  veins,  and  which,  like  the  other  veins  of 
the  brain,  are  destitute  of  valves,  but  present  numerous  bands  or 
cords  stretched  across  their  anterior  so  as  to  prevent  distention. 
The  veins  are  divided  into  superficial  and  deep. 

The  Superficial  veins  are  distributed  over  the  whole  surface, 
mostly  in  the  sulci,  between  the  convolutions ;  they  receive  small 
capillary  branches  from  the  substance,  and  terminate,  those  from 
the  superior  surface  in  the  longitudinal  sinus,  and  those  on  the 
inferior  and  lateral  surfaces  in  the  lateral  and  other  sinuses. 

The  cerebellar  veins  are,  like  the  cerebral,  scattered  over  the 
whole  surface  of  the  cerebellum,  and  mostly  terminate  in  the 
petrosal  sinus. 

The  Deep  or  Ventricular  veins  arise  by  very  minute  branches, 
which  form  intimate  plexuses  in  the  ventricles,  the  chief  being  the 
veins  of  the  corpora  striata,  and  those  of  the  choroid  plexuses, 
uniting  to  form  the  vense  Galeni,  which  leave  the  interior  through 
foramina  at  the  posterior  part  of  the  longitudinal  fissure,  and  ter- 
minate in  the  longitudinal  sinus. 

sinuses. 
The  principal  sinuses  of  the  dura  mater  are  the  superior  and 
inferior  longitudinal,  two  lateral,  two  petrosal,  two  cavernous,  the 
occipital,  and  the  transverse. 


EMERGENT    VEINS.  489 

The  Superior  longitudinal  sinus,  situated  in  the  attachea 
border  of  the  falx  cerebri,  commences  at  the  crista  galli  process, 
and  terminates  at  the  ossific  tentorium,  in  a  reservoir  termed  the 
torcular  'Herophili,  or  confluent  of  the  sinuses,  which  bifurcates 
and  joins  the  lateral  sinuses. 

The  Interior  longitudinal  sinus  is  small,  and  not  always 
present.  It  is  situated  in  the  lower  part  of  the  fals,  below  the 
superior  one,  pursuing  a  similar  course,  and  discharging  into  the 
torcular  Herophili. 

The  Lateral  sinuses,  situated  within  the  folds  of  the  tento- 
rium csrebelli,  receive  the  blood  from  the  longitudinal  sinus,  and 
terminate  in  veins  which  empty  themselves  into  the  temporal 
veins,  through  the  parieto-temporal  conduits. 

The  Petrosal  sinuses,  situated  at  the  sides  of  the  petrosal 
bone,  form  a  communication  between  the  parieto-temporal  con- 
fluents and  the  cavernous  sinuses. 

The  Cavernous  sinuses  are  situated  under  the  dura  mater  at 
the  sides  of  the  sella  turcica,  and  are  united  by  an  arched  branch, 
sometimes  termed  the  transverse  sinus,  which  winds  round  the 
back  of  the  pituitary  gland  ;  posteriorly  they  open  through  the 
foramen  lacerum  basis  cranii  into  the  subsphenoidal  confluent. 
Anteriorly  these  sinuses  lead  to  the  alveolar  veins. 

The  Occipital  sinuses,  which  are  very  irregular,  are  situated 
in  the  falx  cerebelli,  and  terminate,  through  the  condyloid  fora- 
mina, in  the  subsphenoidal  confluent. 


emergent  veins. 

The  venous  blood  from  the  encephalic  sinuses  leaves  the 
cranium  in  various  ways  by  the  emergent  vessels.  These  are 
the  Parieto-temporal  and  Subsphenoidal  confluents,  the  Spinal 
and  Alveolar  veins. 

The  Parieto-temporal  confluent  occupies  the  conduit  of 
the  same  name,  receiving  the  blood  of  the  longitudinal  and  trans- 
verse sinuses,  and  discharging  into  the  temporal  veins,  which 
arise  chiefly  in  this  confluent. 

The  Subsphenoidal  confluent  lies  along  the  side  of  the 
basi-occipital  and  basi-sphenoid  bones,  terminating  anteriorly  in 
a  blind  end.  The  cavernous  sinus  opens  into  it  through  the 
foramen  lacerum  basis  cranii,  the  internal  carotid  artery  passing 
through   the   orifice.     Posteriorly  it  terminates  as  the  anterior 


490 


NETJEOLOGT. 


branch  of  the  occipital  vein,  and  furnishes  branches  leading  to  the 
pterygoid  veins. 

The  Spinal  veins  are  simple  in  their  arrangement,  being  satel- 
lites of  the  several  arteries. 

The  Alveolar  vein  has  already  been  described  as  a  branch  of 
the  glosso-facial  (see  p.  447). 

CRAJSTAL   KERVES. 

The  nerves  which  are  transmitted  through  the  foramina  at  the 
base  of  the  cranium  are  denominated  cranial  nerves.  They  leave 
in  pairs,  regularly -disposed,  one  on  the  right  side  and  the  other 
on  the  left,  and  are  named  numerically,  according  to  the  order 
in  which  they  leave  the  cavity,  and  by  names  derived  from  the 
parts  to  which  they  are  distributed,  or  the  functions  they  perform. 

The  cranial  nerves  are  differently  enumerated  by  different 
authorities,  some  dividing  them  into  nine,  and  others  into 
twelve  pairs.  The  first  classification  is  that  of  Willis,  who 
makes  the  number  correspond  with  the  number  of  foramina 
through  which  they  find  their  exit ;  and  the  last  that  of  Soem- 
merring,  who  counts  the  number  of  the  apparent  roots  of  the 
nerves.  They  are  also  aiTanged  in  three  divisions,  according  to 
their  functions,  as  Nerves  of  special  sensation  ;  Nerves  of  motion  ; 
and  Mixed  or  compound  nerves — that  is,  nerves  which  contain 
both  motor  and  sensory  fibres.  Soemmerring's  classification  is 
the  one  adopted  in  this  work. 


DESIGNATION   OF   THE   CRANIAL   NERVES. 


According  to 

According  to 

Willis's 

Soemmerring's 

According  to  their  Distribution  or  Function. 

Classification. 

Classification. 

1 

1 

Olfactory. 

2 

2 

Optic. 

3 

3 

Motores  oculoruni. 

4 

4 

Pathetici  (trochleares). 

5 

5 

Trifacial  (trigemini). 

6 

6 

Abducenteg. 

7 

{I 

Facial  (portio  dura). 

Auditory  (portio  moUis). 

1    9 

Glosso-pharyngeal. 

8 

ho 

Pneumogastric  (vagus,  par  vagum). 

(11 

Spinal  accessory. 

9 

12 

Hypo-glossal  (sublingual). 

SECOND    PAIR OPTIC   NEEVES. 


491 


FIRST  PAIE — OLFACTORY  NERVES. 

The  olfactory,  or  nerve  of  the  special  sense  of  smell,  arises  by 
i;hree  roots — an  inner,  short  root  of  -white  fibres,  derived  from 
the  inner  and  posterior  part  of  the  anterior  lobe  ;  an  outer,  long 
root,  also  white,  which  crosses  the  Sylvian  fissure  into  the 
greater  lobe,  where  it  is  continuous  with  fibres  of  the  optic 
thalamus ;  and  a  middle  or  grey  root,  which  also  contains  white 
fibres  from  the  corpus  striatum,  and  arises  from  a  papilla  of  grey 
matter  (caruncula)  in  the  mammillary  eminence.  The  union  of 
these  roots  forms  the  olfactory 
lobe,  which,  as  it  passes  forward, 
swells  into  an  oblong  mass,  the 
olfactory  bulb,  which  rests  on  the 
cribriform  plate  of  the  ethmoid 
bone.  From  the  under  part  of 
the  bulb  spring  the  olfactory 
nerve  filaments,  which  pass 
through  the  foramina  in  the  cri- 
briform plate,  and  are  distributed 
in  the  mucous  membrane  of  the 
posterior  part  of  the  nasal  fossa. 
These  filaments  are  divisible  into 
three  groups,  an  outer,  sent  to 
the  turbinated  bones  and  sur- 
face of  the  ethmoid;  a  middle,  fig. i85. 

,  .    ,  , .        , ,  Base  of  the  brain— showing  the  apparent 

which  supplies  the  mucous  mem-         origins  of  the  craniid  nerves,    a,  Olfactory; 

brane  of  the   roof  of  the  fossa;       ^'  ^p"'':  ">  ^°*°"'  '^°^-  ^-  bathetic;  «, 

,  '  Trifacial  ;  /,   Abducens  ;    g,   Portio-dura ; 

and  an  inner,  spread  over  the      a,  PorUo-moiiis;  t,  oiosso-pharyngeai;  *, 

septum  nasi.  Pneumogastric:   I,  Spinal    accessory:   m, 

t^  Hypo-glossaL 


SECOND  PAIR — OPTIC   NERVES. 

The  optic,  or  nerve  of  the  special  sense  of  sight,  is  a  large 
nerve,  which  has  its  deep  origin  in  the  corpora  geniculata,  optic 
thalamus,  and  corpora  quadrigemina ;  the  fibres  from  these  three 
different  sources  uniting  to  form  the  optic  tract,  which  winds 
round  the  brus  cerebri  to  join  its  fellow,  and  form  the  optic  com- 
missure. After  leaving  the  commissure,  the  nerves  become 
rounded,  and  diverge  to  pass  through  the  optic  foramina,  where 
they  receive  a  covering  of  dura  mater,  which  immediately  splits 


^^^  NEUROLOGY. 

into  two  portions,  one  of  which  forms  the  periosteum  of  the  orbit,, 
and  the  other  a  sheath  for  the  nerve.  After  piercing  the  sclerotic 
and  choroid  coats  of  the  eyeball,  the  nerve  expands  into  the 
nervous  retina.  A  little  behind  the  eyeball,  the  nerve  is  pierced 
to  its  centre  for  the  passage  of  a  small  artery,  the  arteria  centralis 
retinae,  which  supplies  the  retina. 

In  the  optic  commissure  a  peculiar  decussation  of  nerve  fibres 
takes  place  ;  while  the  outer  fibres  of  the  optic  tract  continue 
their  course  direct  to  the  eye  of  the  same  side,  the  innermost 
pass  to  that  of  the  opposite  side ;  at  the  same  time,  some  of  the 
fibres  cross  from  one  tract  to  the  other,  and  have  no  connection 
with  the  eyes;  while  others,  it  is  said,  proceed  from  eye  to  eye, 
without  having  commujiication  with  the  brain. 

THIED  PAIR — MOTORES  OCULORUM. 
This,  the  common  motor  nerve  of  the  eye,  has  its  apparent 
origin  on  the  inner  side  of  the  ems  cerebri,  close  to  the  pons 
Varolii,  its  course  lying  between  the  posterior  cerebral  and  anterior 
cerebellar  arteries;  its  deep  origin  may  be  traced  to  the  locus 
niger,  pons  Varolii,  and  corpora  quadrigemina.  It  makes  its  exit 
from  the  cranial  cavity  through  the  foramen  lacerum  orbitale,  into- 
the  orbital  fossa,  where  it  divides  into  several  branches,  supplying 
the  superior,  internal,  and  inferior  recti,  inferior  oblique,  and 
levator  palpebrae  muscles,  and  also  branches  to  the  lenticular 
ganglion. 

FOURTH   PAIR PATHETIC   NERYES. 

This  is  a  motor  nerve,  and  the  smallest  of  the  cranial  nerves  ; 
it  has  its  superficial  origin  by  the  side  of  the  pons  Varolii,  but  its^ 
deep  fibres  may  be  traced  to  the  valve  of  Vieussens  and  the  cor- 
pora quadrigemina.  Winding  round  the  cms  cerebri,  this  nerve 
passes  through  the  outer  wall  of  the  cavernous  sinus,  leaves  the 
cranium  through  the  foramen  patheticum,  and  is  distributed  to 
the  superior  oblique  muscle  of  the  eye.  It  communicates  with 
the  sympathetic,  near  the  cavernous  sinus. 

FIFTH    PAIR TRIFACIAL    NERVES. 

Called  also  the  trigeminal,  this  is  the  largest  of  the  cranial  nerves, 
and,  being  a  nerve  of  common  sensation,  of  motion,  and  indirectly,, 
perhaps,  of  special  sense,  belongs  to  the  class  of  mixed  nerves^ 


FIFTH    PAIR TRIFACIAL    NERVES. 


495 


It'  resembles  a  spinal  nerve  in  having  its  origin  by  two  roots, 
sensory  and  motor,  and  in  having  a  ganglion  on  the  sensory  root. 
It  arises  on  the  side  of  the  pons  Varolii ;  and  the  sensory  root, 
which  is  the  larger,  may  be  traced  to  the  restiforra  bodies  and 
lateral  columns  of  the  cord,  the  motor  root  having  its  deep  origin 
near  the  floor  of  the  fourth  ventricle.  The  nerve  passes  through, 
an  opening  in  the  dura  mater,  at  the  apex  of  the.  petrous  temporal 
bone,  where  the  posterior  root  spreads  out  into  a  large  ganglion, 
the  Gasserian,  the  anterior  root  passing  beneath  without  any 
connection.  The  Gasserian  ganglion  gives  off  the  ophthalmic, 
superior  maxillary,  and  inferior  maxillary  branches. 


Bight  orbit  opened  to  show  the  nerves  of  the  eye.  a  a.  Optic ;  b.  Motor  oculi ;  c,  Patheti  ; 
d.  Ophthalmic  division  of  fifth  pair  ;  d'.  Lachrymal ;  d",  Supraorbital ;  d'".  Nasal ;  e,  AbduceM  ; 
ef,  Eectus  externus  muscle  ;  /,  Orbital  branch  of  superior  majcillary  nerve. 


The  Ophthalmic  nerve,  the  smallest  of  the  three  divisions  of 
the  trifacial  nerve,  passes  forwards  by  the  outer  wall  of  the 
cavernous  sinus,  in  company  with  the  third  and  sixth  nerves, 
enters  the  orbital  fossa  through  the  foramen  lacerum  orbitale,  and 
divides  into  three  branches,  the  frontal,  lachrymal,  and  nasal. 

The  frontal  or  supraorbital  nerve  is  a  large,  flat  branch,, 
placed  on  the  internal  wall  of  the  optic  fossa ;  it  ascends  parallel 
to  the  superior  oblique  muscle,  passes  through  the  supraorbital 
foramen,  and,  after  giving  a  branch  to  the  upper  eyelid,  divides 


494:  NEUROLOGY. 

into  several  branches,  some  distributed  to  the  skin  of  the  fore- 
head, others  to  the  muscles  above  the  eye.  This  nerve  com- 
municates, and  forms  a  plexus  with  the  anterior  auricular  nerve. 

The  lachrymal  nerve,  the  smallest  of  the  three,  passes  straight 
Tip  to  the  lachrymal  gland,  which  it  supplies,  together  with 
branches  to  the  muscles  and  tegument  of  the  anterior  part  of  the 
«ar,  anas^"omosing  with  the  anterior  auricular  nerve. 

The  nasal  or  palpebro-imsal  nerve,  the  largest  branch  of  the 
ophthalmic,  curves  inwards  between  the  retractor  and  levator 
oculi,  and  re-enters  the  cranial  cavity  through  the  internal  orbital 
foramen,  with  the  ophthalmic  artery ;  it  then  passes  through  the 
cribriform  plate  of  the  ethmoid,  and  divides  into  two  branches, 
which  ramify  in  the  pituitary  membrane  on  the  walls  of  the  nasal 
fossa.  Before  entering  the  internal  orbital  foramen,  it  gives  off  a 
long  branch  to  the  membrana  nictitans  and  lower  eyelid,  another 
to  the  lachrymal  sac,  and  sensory  roots  to  the  opnthalmic  gang- 
lion. 

The  Superior  maxillary  nerve  leaves  the  cranium  through 
the  foramen  rotundum,  and  gains  the  orbit  in  company  with  the 
internal  maxillary  artery,  crosses  the  lower  part  of  the  orbit, 
enters  the  maxillary  hiatus,  passes  through  the  infraorbital  or  dental 
canal,  and  emerges  on  the  face,  at  the  infraorbital  foramen,  where 
it  divides  into  numerous  facial  branches.  The  lateral  branches 
of  the  superior  maxillary  nerve  are — 

1.  The  orbital  hranch,  which  leaves  the  trunk  in  the  orbit, 
and  is  distributed  to  the  eyelids  and  integument. 

2.  The  anterior  palatine  or  palato-maxillary,  which  enters 
the  palatine  foramen,  and  accompanies  the  palatine  artery,  giving 
branches  to  the  palate  and  gums. 

3.  The  posterior  palatine,  or  staphyline,  which  accompanies 
the  staphyline  artery,  and  is  distributed  to  the  soft  palate. 

4.  The  spheno-palatine,  or  nasal,  which  passes  through  the 
spheno-palatine  foramen,  is  distributed  to  the  mucous  membrane 
of  the  nasal  chamber,  and  sends  a  branch  to  the  spheno-palatine 
or  Meckel's  ganglion. 

5.  The  dental  branches,  which  are  given  off  behind  and  in 
the  infraorbital  canal,  consist  of  posterior  and  anterior  ;  the 
former  supplying  the  molar  teeth,  and  sending  a  branch  to  the 
maxillary  sinus,  and  the  latter  furnishing  nerves  to  the  incisor 
and  canine  teeth. 

The  terminal  branches  of  the  superior  maxillary  nerve,  supe- 


FIFTH   PAIR TRIFACIAL   NERVES. 


495 


rior,  middle,  and  inferior,  are  distributed  to  the  nose,  false  nostril, 
upper  lip,  and  muscles  and  integument  of  the  face,  and  form 
intimate  plexuses  with  branches  of  the  seventh  pair  or  facial 
motor  nerves. 

The  Inferior  maxillary  nerve,  the  largest  of  the  three 
divisions  of  the  fifth,  unites  with  the  anterior  root  of  the  nerve 
immediately  after  it  passes  through  the  oval  opening  in  the  dura 
mater,  so  that  it  is  both  sensory  and  motor.  The  course  of  this 
nerve  is  through  the  foramen  lacerum  basis  cranii,  and  between 


Fig.  187. 
Nerves  of  the  right  side  of  the  head— the  maxillary  ramus  and  cheek  being  rensoved.  a,  Superior 
maxillary  branch  of  fifth ;  a',  Spheno-palatine  ;  6,  Orbital ;  c.  Branch  of  spheno-palatine ;  d.  Pala- 
tine :  e,  Superior  dental ;  /,  Staphyline  :  o,  Superior  maxillary  trunk  entering  infraorbital  foramen  ; 
g',  Superior  :  g".  Middle  ;  g"'.  Inferior  nasal  nerves  :  li.  Inferior  maxillary  branch  of  fifth ; 
i,  Masseter  ;  k,  Anterior  deep  temporal :  I,  Pterygoid  ;  m.  Buccal ;  b,  Subzygomatic ;  o.  Inferior 
dental;  o',  Mental :  p.  Lingual ;  p',  Its  superficial ;  p".  Its  deep  branch. 

the  pterygoid  muscles,  to  the  inferior  dental  foramen,  which  it 
enters,  and,  passing  through  the  lower  jaw,  makes  its  exit  at  the 
anterior  maxillary  or  mental  foramen,  and  terminates  in  the 
mental  nerves.  In  its  course  it  gives  off  masseter,  buccal,  internal 
pterygoidean,  subzygomatic,  lingual,  mylo-hyoidean,  and  dental 
branches. 

The  masseter  branch  is  detached  from  the  trunk  at  the  base  of 
the  cranium,  passing  through  the  sigmoid  notch  in  front  of  the 


496  NEUROLOGY. 

temporo-maxillary  articulation,  and  is  distribxrted  to  the  masseter 
muscle.      It  gives  off  branches  to  the  temporal  miiscla 

The  buccal  nerve  is  directed  forwards,  traverses  the  external 
pterygoid  muscle,  and  is  distributed  to  the  buccinator  muscle  and 
to  the  mucous  membrane  of  the  cheek,  descending  to  the  com- 
missures of  the  lips  and  the  labial  glands.  In  its  course  it  gives 
small  branches  to  the  external  pterygoid  muscle,  a  branch  (the 
anterior  deep  temporal  nerve)  to  the  temporal  muscle,  and  branches 
to  the  molar  glands.  The  branches  to  the  pterygoid  and  temporal 
muscles  are  for  the  most  part  motor,  the  others  sensory. 

The  pterygoid  nerve  supplies  the  pterygoid  muscles. 

The  suhzygomatic  or  superficial  temporal  nerve  winds  round 
the  ramus  of  the  lower  jaw,  and,  passing  between  the  parotid 
gland  and  the  posterior  border  of  the  jaw,  joins  the  nerves  of  the 
seventh  pair.  In  its  course  it  gives  off  twigs  to  the  guttural 
pouch,  parotid  gland,  and  teguments  of  the  temporal  region. 

The  lingaal,  considered  by  some  authorities  as  the  gustatory 
or  nerve  of  the  special  sense  of  taste,  is  the  principal  branch  of 
the  inferior  maxillary  ;  its  course  lies  between  the  ramus  of  the 
jaw  and  the  pterygoid  muscles,  round  which  it  winds  anteriorly, 
to  reach  the  base  of  the  tongue,  along  the  side  of  which,  under 
the  mucous  membrane,  it  runs  to  the  tip,  giving  off  in  its  course 
numerous  branches  to  the  lingual  papillae,  the  mucous  membrane 
of  the  mouth  and  gums,  and  the  sublingual  gland.  The  lingual 
receives  the  chorda  tympani  branch  of  the  facial,  and  anastomoses 
with  terminal  branches  of  the  twelfth  uerve  ;  it  also  sends  a 
branch  to  the  submaxillary  ganglion. 

The  mylo-hyoidean  nerve  distributes  branches  to  the  mylo- 
liyoideus  and  digas^ricus  muscles,  and  twigs  to  the  subma,xillary 
glands. 

The  dental  branches  are  given  off  in  the  dental  canal,  to 
supply  the  teeth  of  the  lower  jaw;  one  series  supplying  the 
molars,  the  other  the  front  teeth. 

The  mental  or  terminal  branches  of  the  nerve,  issuing  fix>m 
the  mental  foramen,  are  distributed  to  the  lower  lip,  and  com- 
municate with  the  facial  nerve. 

-The  sympathetic  ganglia,  communicating  with  the  fifth  pair, 
are  the  ophthalmic  or  lenticular,  the  spheno-palatine  or  Meckel's, 
■and  the  otic.      (See  Sympathetic  System.) 


SEVENTH   PAIR — PORTIO   DURA,   OR  FACIAL. 


497 


SIXTH   PAIP. ABDUCENS, 

This  is  a  nerve  of  motion,  has  its  apparent  origin  close  behind 
the  pons  Varolii,  at  its  junction  with  the  inferior  pyramids,  and 
its  fibres  can  be  traced  to  the  inferior  pyramids  and  lateral  bundles 
of  the  medulla.  From  its  origin  it  passes  forwards  through  the 
foramen  lacenim  orbitale,  in  company  with  the  third  and  the 
ophthalmic  branch  of  the  fifth  il^:ve3,  aad  is  distiibuted  to  tht 
abductor  oculi,  or  external  rectus,  arid  the  external  portign  of  the 
retractor  oculi  muscles. 


Fio.  188. 

Left  Bide  of  the  f*ee— shoTring  the  listribution  of  the  facial  portions  of  the  fifth  and  the  seventh 
nerves,      a.  Infraorbital ;  6,  Masseter ,  c,  Superior;  d,  Inferior  branch  of  subzygomatic :  c.  An- 
terior ;  /,  Middle  ;  g.  Posterior  auricular ;  h  h,  Posterior  temporal ;  i  Cervical  branch  ;  k,  Styioia 
1 1 1,  Parotid  branches ;  m,  Facial ;  n  n'  n".  Its  superior  portion ;  o.  Its  inferior  portion. 


NTH   PAIR PORTIO   DTJBA,   OS   FACIAL. 

This  nerve  has  its  apparent  origin  in  a  depression  in  the 
medulla  oblongata  between  the  olivary  and  restiform  bodies  ;  its 
deep  origin  can  be  traced  to  the  floor  of  the  fourth  ventricle  and 
olivary  fasciculus.  From  its  origin  it  passes  outwards,  in  company 
with  the  eighth  nerve,  along  with  which  it  enters  the  meatus 
auditorius  internus,  and  thence  into  the  aqueduct  of  Fallopius, 

■2k 


498  NEUROLOGY. 

where  it  bends  upon  itself  and  forms  a  slight  enlargement,  the 
genicular  ganglion,  making  its  exit  through  the  stylo-mastoid 
foramen,  where  it  lies  deeply  buried  beneath  the  parotid  gland. 
Afterwards,  inflected  forwards,  it  passes  between  the  gland  and 
the  guttural  pouch  to  gain  the  posterior  border  of  the  maxilla, 
round  the  cervix  of  which  it  turns,  and,  reaching  the  external 
surface  of  the  masseter  muscle,  terminates  in  two  or  three  branches, 
which  anastomose  with  the  subzygomatic  branch  of  the  fifth, 
forming  the  subzygomatic  plexus.  At  the  genicular  ganglion  the 
seventh  nerve  is  joined  by  a  slender  cord,  the  Tiei^'e  of  Wrisherg, 
which  is  regarded  by  some  authorities  as  the  sensory  root  of  the 
seventh,  by  others  as  a  connecting  medium  between  the  seventh 
and  eighth  nerves. 

In  its  course  the  facial  nerve  gives  off  numerous  branches  ; 
some  before  leaving  the  bone,  the  intraosseous,  and  some  after 
leaving  it,  extraosseous. 

The  intraosseous  branches  are  the  superficial  petrosal,  which, 
leaving  the  genicular  ganglion,  re-enters  the  crauial  cavity  by  the 
Fallopian  hiatus,  and  passing  through  the  cavernous  sinus,  it 
receives  a  branch  from  the  cavernous  plexus  of  the  sympathetic. 
The  nerve  thus  formed — the  Vidian  nerve — traverses  the  fissure 
and  conduit  of  the  same  name  and  gains  the  orbital  hiatus,  where 
it  joins  Meckel's  ganglion,  to  which  it  thus  supplies  motor  and 
sympathetic  roots.  A  little  to  the  outside  of  the  above,  the  lesser 
superficial  peti'osal  iurnishes  motor  fibres  to  the  otic  ganglion, 
and  a  small  filament  supplies  the  stapedius  muscle.  The  cJiorda 
tyrnpani  branch  is  given  off  in  the  aqueduct  of  Fallopius.  It 
enters  the  cavity  of  the  tympanum,  passes  through  the  middle  of 
the  chain  of  small  bones,  or  auditory  ossicles,  and,  leaving  the 
C9,vity  through  the  Glaserian  fissure,  after  a  short  course  under 
the  pterygoid  muscle,  joins  the  lingual  branch  of  the  fifth.  The 
last  intraosseous  branch  is  one  which  anastomoses  with  the 
pueumogastric. 

After  emerging  from  the  stylo-mastoid  foramen,  the  facial 
nerve  gives  off  styloid  branches  to  the  stylo-hyoid  and  digastricus 
muscles ;  a  cervical  branch,  which  passes  downwards  below  the 
deprimens  aurem  muscle  to  the  panniculus  and  skin  of  the  neck  ; 
twigs  to  the  guttural  pouch  and  parotid  gland  ;  and  lastly,  the 
anterior,  posterior,  and  middle  auricular  nerves. 

The  anterior  auricular  nerve  ascends  over  the  front  of  the 
ear,  supplying  the  muscles  and  uniting  with  branches  of  the  fifth. 


NINTH   PAIR — GLCESO-PHAEYNGEAL.  499 

to  form  the  auricular  plesus.  It  gives  twigs  to  the  anterior 
auricular  muscles;  to  the  orbicularis  palpebrarum,  and  levator 
palpebrse  superioris  extern  us.  The  posterior  auricular  nerve 
passes  upwards  with  the  posterior  auricular  artery,  and  supplies 
the  posterior  muscles  of  the  ear  and  the  skin.  The  middle  auri- 
cular nerve  enters  the  concha,  to  the  inner  surface  and  cartilage 
of  which  it  is  distributed. 

The  terminal  or  temporo-facial  branches'  of  the  facial  ijerve 
are  in  two  sets ;  an  inferior,,  which  passes  downwards  to  the 
lov;er  lip  and  muscles  of  the  side  of  the  cheek  and  lower  jaw;  and 
a  superior,  which  supplies  the  muscles  of  the  nose  and  tissues  of 
the  upper  lip.  They  anastomose  with  the  terminal  branches  of 
the  superior  and  inferior  maxillary  divisions  of  the  fifth  nerve, 
and,  from  the  peculiar  looped  and  radiate  manner  of  their  termi- 
nations, have  obtained  the  name  of  pes  anserinus. 

EIGHTH    PAIR PORTIO    MOLLIS,  OR    AUDITORY. 

The  nerve  of  the  special  sense  of  hearing  has  its  origin  on  the 
medulla  oblongata,  close  to  the  facial  nerve.  Its  deep  roots  are 
anterior  and  posterior,  the  one  springing  from  the  central  grey 
matter  of  the  medulla,  and  the  other  from  the  floor  of  the  fourth 
ventricle.  The  auditory  nerve  enters  the  meatus  auditorius 
internus  in  company  with  the  seventh,  and  at  the  bottom  of  the 
passage  divides  into  tv/o  branches ;  an  anterior  or  cochlear,  dis- 
tributed to  the  cochlea,  and  a  posterior  or  vestibular,  which 
supplies  the  vestibule  and  the  remaining  portions  of  the  internal 
ear. 

NINTH    PAIR — GLOSSO-PHARYNGEAL. 

This  is  a  mixed  nerve,  principally  distributed  to  the  tongue 
and.  pharynx,  and  it  arises  from  the  medulla,  the  fibres  composing 
it  being  traceable  to  the  restiform  bodies  and  th'e  olivary  fasciculi. 
It  pierces  the  dura  mater  through  a  distinct  opening,  and  leaves 
the  cranium  through  the  foramen  lacerum  basis  cranii ;  pre- 
viously however  presenting  a  gangliform  swelling,  the  petrosal  or 
AnderscK 8  ganglion,  which  rests  on  the  petrosal  bone.  Leaving 
the  cranium,  it  passes  downwards  and  forwards,  between  the 
guttural  pouch  and  pterygoid  muscles,  and  along  the  posterior 
border  of  the  comu  of  the  os  hyoides,  to  gain  the  base  of  the 
tongue,  being  distributed  to  the  mucous  membrane  and  substance, 
principally  of  the  base  and  sides  of  that  organ. 


500  NEUF.OLOGY. 

Its  branches  are  the  nerve  of  Jacohson,  given  off  from  the 
petrosal  ganglion,  and  distributed  to  the  tympanum  and  its  mem- 
brane ;  filaments  to  the  superior  cervical  ganglion  ;  a  branch  to 
the  carotid  plexus  ;  branches  to  the  muscles  of  the  pharynx ;  and 
a  communicating  branch  to  the  pneumogastric  nerve, 

TENTH  PAIR PAR   VAGUM,  OR   PNEUMOGASTRIC. 

This  is  a  mixed  nerve,  which  originates  by  motor  and  sensory 
roots.  Its  apparent  origin  is  from  a  groove  in  the  medulla  ob- 
longata, immediately  behind  the  ninth  nerve  ;  its  deep  roots  can 
be  traced  to. the  restiform  bodies,  olivary  fasciculi,  and  the  grey 
matter  near  the  floor  of  the  fourth  ventricle.  This  nerve  is 
remarkable  for  its  extent ;  for  the  numerous  dissimilar  organs  to 
which  it  is  distributed  ;  and  for  its  free  and  extensive  anastomoses 
with  other  cerebro- spinal,  and  with  the  sympathetic  nerves.  It 
pierces  the  dura  mater  in  company  with  the  eleventh  nerve,  and 
passes  through  the  foramen  lacerum  basis  cranii,  previously  pre- 
senting an  oblong  grey  mass,  the  jugular  ganglion. 

After  leaving  the  cranium,  the  par  vagum  descends  behind  the 
guttural  pouch,  close  to  the  superior  cervicular  ganglion,  crosses 
to  the  inner  side  of  the  occipital  artery,  arid  joining  the  common 
carotid,  proceeds  down  the  neck  in  the  same  sheath  with  that 
artery.  After  entering  the  thorax,  the  course  of  the  nerve  on 
either  side  varies.  The  right  nerve,  turning  obliquely  round  the 
brachial  artery,  proceeds  backwards  by  the  side  of  the  trachea  to 
the  origin  of  the  bronchi,  where  li  gains  the  under  and  right 
side  of  the  oesophagus;  while  the  left  nerve  passes  along  the 
anterior  aorta,  crosses  the  origin  of  the  posterior  aorta,  and  gains 
the  upper  and  left  side  of  the  oesophagus,  the  two  being  continued 
to  the  stomach  and  the  solar  plexus. 
The  branches  of  the  par  vagum  are — 

1.  An  anastomotic  branch  to  the  facial  near  its  origin. 

2.  Numerous  branches  to  the  superior  cervical  ganglion. 

3.  A  sensory-motor  branch  to  the  pharynx,  which  anastomoses 
with  the  pharyngeal  branch  of  the  nintk 

4.  The  superior  lai^ngeal,  which  passes  to  the  sides  of  the 
larynx,  which  it  enters  through  a  hole  in  the  thyroid  caitilage, 
being  distributed  to  the  mucous  membrane,  and  giving  motor 
fibres  to  some  of  the  muscles  of  that  organ. 

5.  Filaments  to   the   inferior  cervical    ganglion,  two  or  three 


1HNTH    PAIR PAR    VAGUM,    OB    PNEUMoGASTRIC. 


501 


large  ones  being  given  off  by  the  right  nerve,  and  one  long  small 
branch,  by  the  left  nerve, 

6.  The  inferior,  or  recurrent  laryngeal  nerve. — On  the  right 
side,  this  nerve  leaves  the  par  vagum  as  it  passes  the  first  rib, 
and  winds  round  the  origin  of  the  dorsal  artery,  to  gain  the  side 
of  the  trachea.  The  left  one  is  given  off  near  the  root  of  the 
lungs,  and  is  inflected  round  the  posterior  aorta  to  reach  the 
trachea.  Passing  up  the  trachea  below  the  carotids,  the  nerves 
reach  the  larynx,  and  are  distributed  to  all  its  intrinsic  muscles 
excepting  the  crico-thyroideus,  and  giving  off  in  their  course  the 
tracheal  and  the  recurrent  oesophageal  nerves. 


Fio.  189. 
Ninth,  tenth,  eleventh,  and  twelfth  cranial,  first  cervical,  and  part  of  the  sympathetic  nerves— 
the  left  maxillary  ramus  and  parotid  gland  being  removed,  a,  Carotid  artery ;  6,  Glosso-pharynr 
geal ;  V,  Its  pharyngeal ;  6",  Its  Ungual  branch  ;  c  c,  Pneumogastric  ;  c'.  Pharyngeal ;  c",  Superior 
laryngeal ;  d  d'  d",  Spinal  accessory ;  e  e,  Hypo-glcssal ;  /,  Great  sympathetic  ;  /',  Superior  cervical 
ganglion  ;  /",  Anastomosis  of  sympathetic  and  pneumogastric  ;  g.  First  cervical  nerve. 

7.  Cardiac  branches  which  help  to  form  the  cardiac  plexus. 

8.  Numerous  branches  at  the  root  of  the  lungs,  which  form 
the  bronchial  plexus,  from  which  branches  are  distributed  to  the 
divisions  of  the  bronchi,  and  to  the  lungs. 

After  this  plexus  is  formed,  each  par  vagum  is  continued 
along  the  oesophagus  by  a  superior  and  an  inferior  branch. 
After  a  short  course,  the  superior  branches  unite,  and  the  inferior 
l)ranches  doing  the  same,  they  accompany  the  oesophagus,  one 
above  and  the  other  below,  supplying  it  with  numerous  twigs,  till 
they  enter  the  abdomen  through  the  oesophageal  opening  of  the 


502  NEUROLOGY. 

diaphrS/gm,  when  the  inferior  branch  terminates  at  the  lesser 
curvature  of  the  stomach,  in  a  plexus .  which  siends  numerous, 
branches  to  the  right  sac  of  that  organ  ;  and  the  superior  branch, 
passing  to  the  left  of  the  cardiac  orifice,  becomes  lost  in  the  solar 
•plexus.  In  passing  it  gives  numerous  twigs  to  the  left  sac  of 
the  stomach,  mingles  its  branches  with  those  of  the  sympathetic 
from  the  hepatic  plexus,  aad  anastomoses  with  the  terminal  twigs 
of  the  right  nerve. 

ELEVENTH  PAIR — SPINAL  ACCESSORY. 

The  eleventh  is  a  nerve  of  motion,  arising  from  the  whole 
extent  of  the  cervical  portion  of  the  spinal  cord,  running  along 
between  the  roots  of  the  spinal  nerves,  and  after  entering  the 
cranium  by  the  foramen  magnum,  it  receives  additional  filaments 
from  the  medulla  oblongata.  It  passes  through  the  dura  mater, 
in  company  with  the  tenth  pair,  and  leaves  the  cranium  through 
the  foramen  lacerum  basis  cranii.  In  the  cranial  cavity,  it 
receives  twigs  from  the  par  vagum,  and  after  emerging  there- 
from, is  directed  backwards  under  the  superior  extremity  of  the 
submaxillary  gland,  and  passing  down  the  neck,  gains  the  border 
of  the  levator  humeri  muscle  near  the  shoulder  ;  then  mounting 
slightly  upwards,  it  crosses  under  the  cervical  trapezius,  and  is 
lost  in  the  dorsal  trapezius  and  rhorciboideus  brevis  muscles. 

In  its  course  it  gives  off  numerous  twigs  to  the  superior 
cervical  ganglion,  to  the  maxillary  gland,  and  a  large  branch  to 
the  stemo-maxillaris,  levator  humeri,  and  trapezius  muscles,  and 
receives  branches  from  the  first,  second,  third,  fourth,  fifth,  and 
sometimes  sixth  cervical  nerves. 

TWELFTH  PAIR — HYPO-GLOSSAL. 
This,  a  motor  nerve,  has  its  origin  in  numerous  filaments 
derived  from  the  medulla  oblongata.  It  makes  its  exit  from  the 
cranium  by  the  condyloid  foramen  of  the  occipital  bone,  descends 
by  the  external  face  of  the  guttural  pouch,  and  is  distributed  to 
all  the  muscles  of  the  tongue,  after  communicating  with  the  first 
""^rvical  nerve  and  superior  cervical  ganglion  of  the  sympathetic. 

Spinal  Nerves. 
The  nerves  which  emanate  from  the  spinal   cord,  and  make 
their  exit  through  the  intervertebral   foramina  are  collectively 


EXPLANATION  OF  PLATE  VI. 


Nervous  System  of  the  Horse. 


1.  Brain. 

13. 

Solar  plexus. 

2.  Optic  nerve. 

14, 

Semilunar  ganglion. 

a  Superior  maxillary  nerve 

(5th). 

15. 

Tiiimbo-sacral  plexus. 

4.  Inferior  maxillary  nerve 

foth). 

16. 

Anterior  crural  nerve. 

5.  Pneumo-gastric  nerve. 

17. 

Great  sciatic  nerve. 

6.  Medulla  oblongata. 

18. 

External  popliteal  nerve. 

7.  Right  brachial  plexus. 

19. 

External  saphenic  nerve. 

8.  Musculo-cutaneous  nerve. 

20. 

Tibial  nerve. 

9.  Median  nerve. 

21. 

Metatarsal  nerve. 

10.  Radial  nerve. 

22. 

Radial  portion  of  median  nerve 

11.  Cubital  nerve. 

23. 

Metacarpal  nerves. 

12.  Pneumogastric  nerve. 

.  24. 

Digital  branches. 

S.S.  Sympathetic  chain. 
c.  Inferior  cervical  plexus. 
g.  Gutteral  ganglion. 
Sp.  Great  splanchnic  nerve. 
_y.wi.  Posterior  mesenteric  plexus. 
p.  Pelvic  plexus. 


CERVICAL    NERVES.  503 

known  as  the  spinal  nerves.  They  consist  of  forty-two  or  forty- 
three  pairs,  and  are  divided,  according  to  the  regions,  into  eight 
cervical,  seventeen  dorsal,  six  lumbar,  five  sacral,  and  six  or  seven 
coccygeal  pairs.  The  whole  of  the  spinal  nerves  originate  by  two 
orders  of  roots,  superior  or  sensory,  and  inferior  or  motor ;  the 
former,  which  are  larger  and  more  numerous,  arising  from  the 
superior  lateral  fissure,  and  the  latter  from  the  inferior  lateral 
fissure  of  the  cord.  In  the  intervertebral  foramina  there  is  a 
ganglion  on  each  of  the  superior  roots,  underneath  which  the 
inferior  root  passes.  The  .union  of  the  two  roots  constitutes  the 
spinal  nerve,  which,  almost  immediately  after  it  passes  through 
the  foramen,  divides  into  two  branches  ; '  a  superior,  distributed 
to  the  spinal  muscles  and  the  integument  which  covers  them ; 
and  an  inferior,  longer  and  larger,  distributed  to  the  inferior 
and  lateral  parts  of  the  trunk,  and  in  some  cases  the  extremities. 
The  spinal  nerve  sends  various  communicating  branches  to  the 
sympathetic  system. 

CERVICAL    NERVES  (8  pairs). 

The  first  cervical  nerve,  the  suboccipital  of  Willis,  leaves  the 
spinal  canal  through  the  internal  foramen  of  .the  atlas ;  the 
second  through  a  foramen  in  the  anterior  part  of  the  axis,  the 
succeeding  five  through  the  corresponding  intervertebral  fora- 
mina, and  the  eighth  between  the  last  cervical  and  first  dorsal 
vertebra. 

Superior  Branches.  —  The  superior  division  of  the  first 
nerve,  after  reaching  the  interstice  between  the  anterior  oblique 
and  the  posterior  straight  muscles  of  the  head,  divides  into 
numerous  branches,  which  are  distributed  to  the  muscles  at  the 
back  of  the  poll  and  to  the  retrahentes  muscles  of  the  ear  ; .  one 
long  branch,  which  anastomoses  with  the  posterior  auricular 
branch  of  the  seventh  cranial  nerve,  to  form  the  auricular  plexus, 
is  sent  to  the  concha,  and  the  skin  covering  it. 

The  superior  division  of  the  second  nerve,  situated  under  the 
obliquus  capitis  posticus  muscle,  to  which  and  the  anterior 
oblique  it  gives  branches,  is  distributed  in  a  similar  manner  to 
the  superior  branches  of  the  remaining  cervical  nerves.  These, 
gradually  diminishing  in  size  as  they  proceed  backward,  pierce 
the  intertransversalis  muscle,  and  divide  into  superficial  branches, 
distributed  to  the  superficial  muscles  and  skin,  and  the  deejy 
branches,  larger  than  the  others,  which  cross  the  transverse  pro- 


504  NEUROLOGY. 

cesses,  and  form  the  deep  cervical  plexus,  from  which  the  deep 
muscles  are  supplied. 

Inferior  Branches. — The  inferior  divisions  of  the  cervical 
nerves  gradually  increase  in  size  from  the  first  to  the  last.  They 
separate  into  two  distinct  groups,  composed  of  the  anterior  six, 
which  furnish  branches  to  the  muscles  and  skin  of  the  breast, 
and  of  the  lateral  and  anterior  part  of  the  neck,  transmitting 
intercommunicating  branches,  which  form  a  vast  network  known 
as  the  superficial  cervical  plexus,  and  which  is  traversed  by 
the  cervical  branch  of  the  facial  and  an  important  branch  from 
the  spinal  accessory  nerves.  The  last  two,  together  with  a  branch 
from  the  sixth,  join  the  two  first  dorsal  nerves  to  form  the 
brachial  plexus. 

The  inferior  branches  of  the  first  cervical  nerve  pass  through 
the  foramen  in  front  of  the  atlas  in  company  with  the  occipital 
artery  and  vein,  cross  the  rectus  capitis  anticus  major  muscle, 
and  the  spinal  accessory  nerve,  and,  describing  a  curve  towards 
the  top  of  the  trachea,  enter  the  subscapulo-hyoideus  muscle, 
where  they  terminate  in  numerous  branches.  In  their  course 
they  furnish  filaments  to  the  three  recti  muscles,  to  the  thyro- 
hyoid, sterno-thyro-hyoideus,  sterno-maxillaris,  and  the  muscles 
connecting  the  hyoid  bone  to  the  laiynx,  and  communicate  with 
the  superior  cervical  ganglion,  the  spinal  accessory,  and  hypo- 
glossal nerves. 

The  inferior  branch  of  the  second  cervical  nerve  descends  under 
the  posterior  oblique,  and  is  distributed  by  numerous  branches  to 
the  rectus  capitis  anticus  major  and  minor,  levator  humeri, 
deprimens  aurem,  retrahentes  aurem,  and  subscapulo-hyoideus 
muscles  ;  to  the  outer  side  of  the  concha,  and  to  the  panniculus 
and  skin,  communicating  with  a  branch  of  the  spinal  accessory 
and  cervical  branch  of  the  facial  nerves,  and  with  the  inferior 
cervical  ganglion  of  the  sympathetic. 

The  inferior  branches  of  the  third,  fourth,  fifth,  and  sixth 
cervical  nerves  pass  through  the  intertransverse  muscle,  and  divide 
into  deep  and  superficial  branches,  the  one  being  distributed  to 
the  deep  muscles  of  the  neck  and  anterior  part  of  the  shoulder, 
and  the  other  to  the  skin  of  the  neck  and  the  panniculus.  The 
deep  branches  of  the  sixth  and  seventh,  and  a  filament  from  the 
fifth  help  to  form  the  phrenic  or  diaphragmatic  nerve. 

The  seventh  cervical  nerve,  a  very  large  nerve,  passes  between 
the  two  portions  of  the  scalenus  muscle,  and  helps  to  form  the 


LUMBAE   NERVES.  505 

Irachial  plexus.      It  receives  an  anastomosing  branch  furnished 
by  the  sisth  nerve. 

The  eighth  cervical  Tierve,  larger  than  the  preceding,  also 
passes  to  the  brachial  plexus.  It  sends  a  branch  to  the  inferior 
cervical  ganglion. 

D0E3AL   NERVES    (17    pairs). 

The  dorsal  nerves,  with  the  exception  of  the  first,  are  all  dis- 
tributed  in  a  similar  and  very  simple  manner,  as  compared  with 
the  cervical  nerves.  The  superior  branches,  passing  up  between 
the  transverse  processes,  bifurcate,  one  branch  being  sent  to  the 
spinal  muscles  and  the  skin  of  the  dorsal  region,  the  other  being 
distributed  to  the  longissimus  dorsi  muscle.  The  inferior 
branches  descend  to  the  intercostal  spaces,  ::nd  pass  along 
between  the  pleura  and  internal  intercostal  muscles.  Each  of 
these  intercostal  nerves,  at  its  origin,  gives  one  or  two  branches 
to  the  sympathetic,  and,  towards  its  middle,  a  perforatina  branch 
directed  obliquely  outwards  to  the  skin,  where  it  ramifies,  pnd  in 
Its  course,  gives  oflf  muscular  filaments. 

The  inferior  branch  of  the  First  Dorsal  nerve  goes  almost 
entirely  to  the  brachial  plexus.  It  has  no  cutaneous  division 
and  uc  intercostal  branch  is  very  slender. 

llie  Second  Dorsal  nerve  sends  a  large  branch  to  the 
bracbid  plexus.  Its  intercostal  branch,  more  considerable  than 
th.H  of  the  first,  extends  down  to  the  sternum,  and  gives  off 
cutaneous  twigs. 

The  Third,  Fourth,  Fifth,  Sixth,  Seventh,  and  Eighth 
UOEs.^L  NiaiVES  pass  to  the  extremity  of  the  intercostal  spaces 
and  are  prolonged  into  the  pectoralis  magnus  and  rectus  muscles  • 
tnetast  mne,  after  reaching  the  cartilages  of  the  false  r.-bs  are' 
contmued  into  the  walls  of  the  abdomen,  and  under  the  internal 
oblique,  to  the  rectus,  where  they  divide,  one  division  going  to 
the  substance  of  the  muscles,  the  other  furnishing  twigs  to  the 
skin  of  the  abdomen.  The  Seventeenth  Dorsal  nerve  fur- 
nishes a  large  branch  to  the  fleshy  portion  of  the  internal  oblique, 
and  another  which  anastomoses  with  the  first  lumbar  nerve. 

LUMBAR    NERVES    (6    pairs). 

The  Superior  branches  of  the  lumbar  nerves  are  distributed 
to  the  muscles  of  the  loins,  and  to  the  integument  of  the  loins 
and  croup. 


506  NEUROLOGY. 

The  Inferior  branches  send  twi,srs  to  the  sympathetic,  and 
branches  which  anastomose  with  one  another. 

That  of  the  first  lumbar  nerve  receives  a  branch  from  the  last 
dorsal,  and  turning  backwards  under  the  transverse  process  of 
the  second  lumbar  vertebra,  passes  between  the  transversalis 
abdominis  and  internal  oblique,  to  which  it  sends  filaments,  and 
terminates  in  the  rectus  muscle.  Near  its  origin,  it  gives  off  a 
perforating  branch  which,  passing  through  the  abdominal  muscles, 
terminates  in  numerous  cutaneous  filaments. 

The  inferior  branch  of  the  second  lumbar  nerve  has  similar 
anastomosing  branches  to  the  first,  and  two  perforating  nerves 
which,  receiving  a  small  branch  from  the  third,  descend  under 
the  skin  of  the  internal  and  anterior  face  of  the  thigh,  and  are 
distributed  to  the  skin  of  the  flank  and  the  crural  region. 

The  inferior  branch  of  the  third  nerve,  besides  its  anastomosing 
branches,  sends  usually  three  branches  downwards  and  outwards 
to  the  inguinal  canal,  where  they  ramify  in  the  cremaster  muscle ; 
it  also  furnishes  numerous  twigs  to  thj8  psoas  magnus.  One  of 
the  inguinal  nerves  generally  unites  with  a  large  branch  of  the 
fourth  nerve. 

The  inferior  branch  of  the  fourth  lumbar  nerve,  besides  the 
branches  common  to  all,  gives  a  large  branch  to  the  lumbo-sacral 
plexus,  and  a  long  branch  which  unites  with  an  inguinal  branch 
from  the  third.  It  is  then  directed  downwards  to  the  thigh, 
where  it  terminates  in  numerous  cutaneous  and  aponeurotic 
branches. 

The  fifth  lumbar  gives  a  large  branch  to  the  lumbo-sacral 
plexus,  and  branches  to  the  psoas  parvus. 

The  sixth  lumbar  is  the  principal  branch  of  the  lumbo-sacral 
plexus. 

SACRAL  NERVES  (5  pairs). 

The  sacral  nerves,  which  diminish  in  size  from  the  first  to  thfe 
last,  have  their  origin  close  to  each  other,  their  roots  surrounding 
the  conus  meduUaris,  in  which  the  spinal  cord  terminates,  and  by 
which  it  extends  into  the  canal  of  the  sacrum.  With  the  coccy- 
geals they  form  the  nerve  tuft  known  as  the  cauda  equina. 

The  superior  branches  of  the  sacral  nerves  leave  the  spinal 
canal  through  the  superior  sacral  foramina,  and  are  distributed 
to  the  muscles  of  the  superior  region  of  the  sacrum,  and 
terminate  in  the  skin  of  the  croup. 


PHRENIC    NERVE.      •  50T 

The  inferior  branches,  the  first  three  of  which  assist  in  the 
formation  of  the  lumbo-sacral  plexus,  converge  at  the  side  of  the 
pelvic  cavity.  The  fourth  constitutes  the  internal  pudic  nerve, 
which,  at  its  origin,  sends  an  anastomosing  branch  to  the  origin 
of  the  fifth.  It  is  distributed  to  the  penis,  where  it  terminates, 
by  numerous  branches,  in  the  glans.  Before  leaving  the  pelvic 
cavity,  it  sends  filaments  to  the  muscles  and  skin  of  the  perineo- 
ai-al  region.  In  the  female,  this  nerve  is  distributed  to  the 
parts  analogous  to  those  of  the  male. 

The  fifth  forms  the  anal  or  hcemorrhoidal  nerve,  distributed 
to  the  sphincter  ani,  and  the  skin  covering  it. 

Small  filaments  which  form  the  pelvic  or  hypogastric  plexus 
are  given  oflf  from  near  the  origins  of  all  the  sacral  nerves. 

COCCYGEAL   NERVES  (6  or^  7  pairs). 

The  coccygeal  nerves  differ  from  the  other  spinal  nerves  in 
having  no  immediate  communication  with  the  sympathetic. 
They  diminish  in  size  from  the  first  to  the  last.  The  superior 
branches  unite  to  form  one  large  nerve,  which  passes  under  the 
curvator  coccygis  muscle,  and  extends  to  the  tip  of  the  tail, 
giving  off  muscular  and  cutaneous  filaments  in  its  course  ;  the 
inferior  branches  likewise  coalesce  and  extend  in  a  similar- 
manner  under  the  depressor  muscle. 

The  inferior  branch  of  the  first  coccygeal  receives  a  branch 
from  the  last  sacral,  and  sends  a  filament  down  towards  the  anus 
and  perinaeum. 

NERVES  FORMED  BY  THE  INFERIOR  BRANCHES  OF  THE 
SPINAL  NERVES. 

These  nerves  form  three  groups,  as  follows  : — The  Phrenic 
nerve,  the  Brachial  plexus,  the  Lumbo-sacral  plexus. 

PHRENIC   NERVE. 
{Fig.  195.  9  g  g.) 

The  phrenic  or  diaphragmatic,  the  motor  nerve  of  the  dia- 
phragm, is  formed  by  three  principal  branches;  one  from  the 
brachial  plexus,  one  from  each  of  the  sixth  and  seventh  cervical 
nerves,  with  a  filament,  not  constant,  from  the  fifth.      It  enters 


•508  NEUROLOGY. 

the  thoracic  cavity,  and  passing  to  the  inner  side  of  the  brachial 
artery,  receives  a  filament  from  the  sympathetic  ;  thence  it  travels 
between  the  two  layers  of  the  mediastinum,  and  reaching  the 
aponeurotic  centre  of  the  diaphragm,  divides  into  numerous 
branches,  which  are  carried  towards  the  periphery  of  the  muscle. 

BRACHIAL   PLEXUS. 
(Fig.  190.) 

The  brachial  plexus  comprehends  that  large  bundle  of  nerves 
formed  of  the  inferior  branches  of  the  seventh  and  eighth  cervical, 
the  first  and  part  of  the  second  dorsal  nerves,  all  of  which 
converge  to  the  interstice  between  the  two  divisions  of  the 
scalenus  muscle,  where  they  unite,  and  pass  outwards  round  the 
■first  rib.  At  and  below  the  arm,  the  plexus  divides  into  numer- 
ous branches,  distributed  to  the  muscles  and  teguments  of  the 
anterior  extremity  ;  the  chief  branches  we  describe  as  follows  : — 

The  Anterior  scapular  nerve  is  a  large  branch  which 
supplies  the  muscles  on  the  dorsum  of  the  scapula ;  it  turns 
round  the  anterior  border  of  the  bone,  a  little  above  its  neck, 
passing  under  the  antea-spinatus,  to  which  and  to  the  postea- 
spinatus  it  gives  twigs,  terminating  in  the  latter. 

The  Thoracic  nerve  consists  of  six  or  seven  branches  of 
unequal  size  and  length,  usually  distributed  to  the  muscles 
between  the  shoulder  and  the  trunk ;  three  anterior  ones  are 
■directed  obliquely  downwards,  losing  themselves  in  the  muscles 
attached  to  the  sternum  ;  while  of  the  three  posterior  branches, 
one,  winding  I'ound  the  posterior  border  of  the  caput  muscles, 
becomes  superficial,  and  is  distributed  to  the  panniculus  and 
skin ;  while  the  remainder  are  distributed  to  the  latissimus  dorsi 
and  serratus  magnus. 

The  Subscapular  nerve  includes  two  principal  cords,  the 
smaller  of  which  goes  to  the  subscapularis,  and  the  larger,  the 
axillary  or  circumflex  nerve,  turning  round  the  scapulo-humeral 
articulation,  terminates  in  a  subcutaneous  branch  which  descends 
the  arm.  It  supplies  the  subscapularis,  teres  externus,  and 
levator  humeri,  and  furnishes  articular  and  cutaneous  filaments. 

The  Radial  nerve,  a  large  branch  of  the  brachial  plexus,  is 
principally  furnished  by  the  first  dorsal.  It  arises  behind  the 
humeral  artery,  and  is  directed  backwards  and  downwards  under 
the  subscapularis  and  teres  major  muscles,  being  accompanied  for 


BRACHIAL    PLEXUS. 


509^ 


a  short  distance  by  the  artery.  Near  the  deep  humeral  artery,, 
it  turns  round  the  back  of  the  humerus,  between  the  caput  mag- 
num and  humeralis  obliquus,  and  passing  down  the  outer  surface 
of  the  bone,  gains  the  anterior  face  of  the  elbow  joint  and  radius, 
where  it  meets  the  anterior  radial  artery,  and  accompanies  it 
almost  as  far  as  the  carpus,  supplying  the  extensor  muscles  of 
the  forearm.      In   its'  course  it  gives  off  branches  to  the  caput 


Fig.  190. 

Internal  aspecb  of  right  anterior  extremity  —  showing  the 
brachial  plexiis.  a,  Seventh  cerrical  nerve  ;  6,  Eighth  cervical 
nerve ;  c.  First  dorsal  nerve ;  d,  Branch  from  second  dorsal 
nerve  ;  c,  Anterior  thoracic ;  /,  Posterior  thoracic ;  g.  Anterior 
scapular;  h.  Subscapular;  i.  Axillary;  7;,  Cubital;  I,  Small 
mnsculo-cutaneous  branch  ;  m,  Radial;  n,p,  Median;  o,  Musculo- 
cutaneous. 


muscles  and  scapulo-ulnaris,  to  the  elbow  joint,  and  to  the   skin 
covering  the  arm. 

The  Ulnar  or  Cubital  nerve  is  formed  of  fibres  from  the 
dorsal  nerves  ;  it  is  less  than  the  radial,  and  originates  on  the 
outer  side  of  the  humeral  artery,  which  it  accompanies  beyond 
the  origin  of  the  deep  humeral  artery ;    crossing  the  latter,  and 


510 


NEUROLOGY. 


WlBIl 


passing  between  the  scapulo-ulnaris  and  caput  parvum  muscles, 
it  gains  the  inner  side  of  the  elbow.  Afterwards,  descending  to 
the  bend  of  the  carpus,  it  passes  under  the  annular  ligament  and 
divides  into  two  branches,  one  of  which  unites  with  a  branch 
from  the  median,  to  constitute  the  external  metacarpal  nerve,  and 
the  other,  traversing  the  space  between  the  tendons  of  the  flexor 
metacarpi  externus  and  medius,  is  distributed  by  numerous 
branches  to  the  skin  covering  the  radius, 
carpus,  and  the  outer  side  of  the  metacarpus. 
This  nerve  accompanies  the  artery  and  vein  of 
the  same  name. 

In  its  course,  the  ulna  nerve  gives  off,  a 
branch  which  proceeds  downwards  between  the 
scapulo-ulnaris  and  pectoralis  trans  versus,  fur- 
nishing many  filaments  to  the  latter ;  be- 
coming cutaneous,  it  is  distributed  to  the  skin 
below  the  elbow.  It  also  furnishes  a  branch 
to  the  flexor  metacarpi  muscles. 

The  Median  nerve,  composed  of  fibres 
from  the  two  dorsal  and  the  eighth  cervical 
nerves,  descends  the  humerus  in  company  with 
the  humeral  artery  to  the  inner  side  of  the 
elbow,  runs  down  the  side  of  the  radius  till  it 
reaches  the  carpus,  and  then,  passing  under 
the  posterior  annular  ligament,  divides  into 
the  internal  metacarpal,  and  a  branch  to  the 
external  metacarpal  nerve.  In  its  course  it 
gives  off,  under  the  brachial  artery,  a  branch 
to  the  pectoral  muscles  ;  and  near  the  middle 
of  the  humerus,  a  long  branch,  the  quuscuIo- 
cutaneous  or  antibrachial  nerve,  which  passes 
obliquely  under  the  coraco-humeralis  and 
coraco-radialis  muscles ;  here  it  divides,  one 
branch  going  to  the  humeralis  externus,  while 
the  other,  passing  between  this  muscle  and 
the  coraco-humeralis,  gains  the  inner  aspect  of 
the  arm,  where  it  becomes  subcutaneous,  and  ramifies  on  the 
antibrachial  fascia,  sending  its  branches  down  to  the  carpus.  The 
median  nerve  also  supplies  numerous  filaments  to  the  elbow  joint, 
to  the  flexor  muscles  of  the  phalanges,  and  the  internal  flexor  of 
the  metacarpus. 


Fig.  191. 
Carpal  and  metacarpal 
nerves— internal  aspect. 
q.Exterualbranch  of  medi- 
an ;  r.  Internal  branch  of 
median,  or  internal  meta- 
carpal ;  s,  Internal  branch 
of  cubital  ;  s'.  External 
branch  of  cubital ;  t,  Exter- 
nal branch  of  median,  and 
internal  branch  of  cubital 
uniting  to  form  external 
metacarpal  ;  u,  Anasto- 
motic branch  uniting 
metacarpal  nerves  ;  v,  In- 
ternal digital. 


LUJ*uiu-SACRAL    PLEXUS.  511 

The  Metacarpal  nerves,  external  and  internal,  are  formed, 
the  fir^t  by  the  union  of  a  branch  from  the  median  and  one  from 
the  cubital  ;  the  second  may  be  regarded  as  the  continuation  of 
the  median.  They  run  down  the  metacarpus  by  the  sides  of  the 
flexor  tendons,  to  which  they  give  filaments,  and  terminate  at 
the  fetlock  ;  the  internal  nerve  lies  posterior  to  the  great  meta- 
carpal artery.  Midway  down  the  metacarpus,  they  anastomose 
by  means  of  an  oblique  branch  which  crosses  the  flexor  tendons 
posteriorly.  At  the  fetlock,  near  the  insertion  of  the  suspensory 
ligament  to  the  sesamoids,  each  metacarpal  nerve  divides  into 
tliree  digital  branches ;  anterior,  middle,  and  posterior. 

The  anterior  branch  descends  in  front  of  the  digital  vein,  and 
distributes  its  branches  on  the  anterior  surface  of  the  foot.  The 
middle  branch  frequently  anastomoses  with  the  others,  and  always 
•with  the  anterior  branch.  It  supplies  the  fetlock  pad  and  sensi- 
tive sole.  The  posterior  branch,  by  far  the  largest,  and  the  true 
continuation  of  the  metacarpal  nerve,  is  continued  behind  the 
digital  artery  to  the  basilar  process  of  the  os  pedis,  entering  the 
lateral  fissure,  and  being  distributed  to  the  substance  of  the  bone 
and  the  laminae.  It  gives  ofi"  branches  to  the  flexor  tendons, 
and  a  filament  which  is  carried  forwards  and  distributed  to  the 
sensitive  frog ;  minute  filaments  accompany  the  plantar  ungual 
artery  into  the  pedal  bone. 


LUMBO-SACRAL  PLEXUS. 
(Fig.  192.) 

This  plexus,  which  supplies  the  posterior  extremity,  is  formed 
by  the  inferi^  branches  of  the  last  two  lumbar  and  the  first  three 
sacral  nerves ;  it  is  divided  into  two  portions,  an  anterior  or 
lumbar,  and  a  posterior  sacral,  each  of  which  has  a  large  trunk 
for  its  centre.  The  anterior  division  is  constituted  by  the  above- 
mentioned  lumbar  nerves,  receiving,  after  a  short  course,  a  branch 
from  the  fourth  one ;  the  posterior  division  is  formed  by  the  first 
three  sacral  nerves,  which  unite  to  form  a  single  bundle.  These 
trunks  are  united  by  communicating  branches. 

The  anterior  division  is  buried  under  the  psoas  parvus,  and 
is  separated  from  the  posterior  division  by  the  internal  iliac  artery. 
The  posterior  division  is  placed  within  and  on  the  side  of  the 
peivio  cavity.  The  anterior  division  furnishes  the  iliaco-mus- 
-cular,  crural,  and  obturator  nerves.     The  posterior  division  gives 


512  NEUROLOGY. 

off  ilio-ynuscular  and  iscliio-muscvdar  or  lesser  sciatic  branches^ 
and  terminates  as  the  great  sciatic  nerve. 

The  Iliaco-muscular  are  numerous  small  branches,  the  chief 
of  which  accompany  the  iliaco-muscular  artery  across  the  iliacus 
muscle. 

The  Crural  or  Anterior  Femoral  nerve  is  the  largest 
branch  of  the  anterior  division.  It  descends  betvfeen  the  psoas 
magnus  and  psoas  parvus,  and  passing  under  the  sartorius,  enters 
between  the  rectus  femoris  and  vastus  internus,  distributing 
branches  to  these  muscles.  Near  the  groin,  it  gives  off  the 
internal  saphenic  nerve,  which  accompanies  the  femoral  artery 
for  some  little  distance,  then  passes  between  the  sartorius  and 
gracilis,  becoming  subcutaneous,  and  passing  down  the  limb,  in 
company  with  the  internal  saphena  vein,  and,  on  the  inner  face 
of  the  leg,  it  is  continued  to  the  hock,  and  by  delicate  branches 
as  far  as  the  fetlock  and  pastern.  Another  long  subcutaneous 
branch  is  given  off,  which  breaks  up  and  surrounds  the  saphenic 
artery  and  vein.  These  branches  furnish  filaments  to  the  stifle, 
to  the  adductor  and  pectineus  muscles,  and  to  the  skin  of  the 
anterior  and  inner  part  of  the  leg. 

The  Obturator  nerve,  situated  at  first  under  the  peritoneum, 
accompanies  the  obturator  artery  through  the  obturator  foramen, 
and  gaining  the  muscles  on  the  internal  face  of  the  thigh,  ter- 
minates in  the  obturator  extemus,  adductors,  pectineus,  and 
gracilis,  also  giving  twigs  to  the  obturator  internus. 

The  Ilio-muscular  or  Anterior  Gluteal  nerves,  four  or 
five  in  number,  leave  the  pelvis  through  the  great  sciatic  notch. 
The  principal  branch  loses  itself  in  the  gluteus  maximus,  another 
crossing  the  neck  of  the  ilium,  above  the  gluteus  internus,  is 
directed  outwards,  and  distributed  to  the  tensor  fascise  latse. 
Another  passes  to  the  gluteus  internus,  in  the  substance  of  which 
it  terminates. 

The  Ischio-muscular  or  Posterior  Gluteal  nerves  are  ihe 
superior  and  inferior.  The  first,  the  course  of  which  lies  through 
the  sciatic  notch,  and  between  the  sacro-sciatic  ligament  and  the 
gluteus  maximus  muscle,  to  the  posterior  portion  of  which  it  gives 
a  small  branch  in  passing,  and  sends  another  to  the  gluteus 
externus,  terminating  by  numerous  branches  in  the  triceps 
abductor  muscle.  The  second  is  situated  below  the  preceding, 
and  supplies  the  biceps  rotator  tibialis  muscle  and  skin  of  the 
posterior  part  of  the  haunch. 


LUMBO- SACRAL    PLEXUS. 


513 


The  Great  Sciatic  nerve,  the  largest  nerve  in  the  body, 
leaves  the  pelvis  in  company  with  the  gluteal  nerves,  through  the 
great  sciatic  notch,  and  is  directed  downwards  along  the  posterior 
face  of  the  femur.  Near  the  stifle,  it  passes  between  the  two 
portions  of  the  gastrocnemius  muscle,  where  it  forms  two 
branches ;  a  short  one,  which  enters  the  muscles  attached  to  the 
posterior  part  of  the  tibia,  and  is  distributed  to  the  flexor  pedis, 
popliteus,  and  flexor  pedis  accessorius  muscles  ;  and  a  principal 


Flu.  192. 

Lumbo-sacral  plexus  of  the  right  side — the  pelvis  opeied  a  id  viscera  removed,  a.  First  lumbar 
nerve :  a'  a",  Its  branches ;  6,  Second  lumbar  nerve  :  c.  Inguinal  branch  :  d.  Femoral  cutaneous  : 
e.  Crtiral ;  e'.  Internal  saphenic  ;  /,  Obturator  :  g,  Anterior;  and  h,  Posterior  gluteal;  i,  Posterior 
cutaneous  branch;  fc.  Internal  pudic ;  k',  Its  perineal  branch  :  fc",  Dorsal  branch  to  the  penis;  I, 
Haemorrhoidal  ;  to  m,  Great  sciatic :  m'.  Posterior  crural :  m".  External  popliteal :  m'",  External 
saphenic :  n.  Muscular  branch  ;  o,  TibiaL 


branch,  the  tibial  or  popliteal  nerve,  which  descends  at  the 
posterior  part  of  the  tibia,  below  the  flexor  perforatus,  and 
divides  at  the  hock  into  external  and  internal  metatarsal 
branches.  In  its  course,  the  sciatic  nerve  furnishes  filaments  to 
all  the  muscles  situated   at  the  posterior  part  of  the   thigh,  with 

2l 


514 


NEUHOLOGY. 


two  important    braoches,  the    external    popliteal    and    external 
saphenic  nerves. 

The  External  Popliteal  nerve  leaves  the  great  sciatic 
about  the  level  of  the  geraelli  muscles.  It  passes  between  the 
adductor  magnus  and  gastrocnemius,  and  arrives  at  the  supe- 
rior extremity  of  the  leg,  behind  the  lateral  ligament  of  the 
femoro-tibial  articulation,  when  it  terminates  in  two  branches; 
one,  the  anterior  tibial  nerve,  is  short,  and  enters  the  muscles 
attached  to  the  superior  extremity  of  the  anterior  face  of  the 
tibia,  in  which  it  ramifies ;  the  other  the  rausculo-cvianecnis 
nerve  turns  downwards  by  the  outer  side  of 
the  anterior  surface  of  the  leg,  and,  passing 
the  hock,  metatarsal  bone,  and  fetlock, 
terminates  at  the  pastern.  It  gives  off 
numerous  muscular  and  cutaneous  filaments. 
The  External  Saphenic  nerve  is  given 
off  shortly  before  the  great  sciatic  enters  the 
gastrocnemius  muscle,  descending  under 
the  fascia  which  covers  the  latter,  and 
accompanying  the  external  saphenic  vein. 
It  passes  the  tarsal  joint,  and  ramifies  on 
the  external  aspect  of  the  metatarsus,  some 
of  its  filaments  reaching  the  digital  region. 
In  addition  to  the  above,  a  small  nerve 
is  given  off  from  the  great  sciatic  to  supply 
the  ischio-femoralis,  gemelli,  and  obturator 
intern  us  ;  also  a  large  branch,  the  posterior 
crural,  aris3S  as  the  sciatic  nerve  bends 
downwards  over  the  femur,  and  supplies  the 
muscles  of  the  lateral  and  posterior  femoral 
regions.  A  fasciculus  of  nerves,  given  off  as 
the  sciatic  enters  the  gastrocnemii,  assists  in 
supplying  the  posterior  tibial  group -^i  jauscles. 
The  External  and  Internal  Metatarsal  InERves,  formed 
by  the  bifurcation  of  the  great  sciatic,  pass  down  the  side  of  the 
flexor  tendons,  and  terminate  as  the  digital  nerves.  Towards  the 
superior  extremity  of  the  cannon  bone,  the  external  metatajrsai 
nerve  is  earned  outwards  between  the  splint  bone  and  the  tendon, 
while  the  internal  one  is  placed  on  the  inner  side  of  the  tendon, 
and  foUows  the  posterior  border  of  the  inner  splint.  The  digiiui 
nerves  are  distributed  in  a  similar  manner  to  those  of  the  fore  foot. 


Pio.  193. 
Tarsal  and  metatarsal  nerves 
—internal  aspect.  <r,  Internal 
cutaneous  branch  ;  I,  External 
metatarsal ;  c,  Internal  meta- 
tarsal; (I,  Their  counectins 
branch  ;  e.  Internal  digital. 


CEPHALIC   PORTION    OF    THE    SYMPATHETIC    SYSTEM. 


515 


Sympathetic  System. 

The  sympathetic  or  ganglionic  system  of  nerves,  the  nerves  of 
organic  life,  consists  of  two  large  cords  or  chains  of  nerves,  which 
extend  from  'the  head  to  the  posterior  extremity  of  the  sacrum, 
tmder  the  lateral  parts  of  the  bodies  of  the  vertebrae,  on  each  side 
of  the  column.  These  nerve  cords  are  furnished  with  a  number 
of  ganglia,  whSxih  both  give  and  receive  numerous  communicating 
filaments  from  the  cerebro-spinal  nerves. 

A  sympathetic  ganglion  is  a  nerve  centre,  to  which  converge 
various  so-called  afferent  branches,  motor,  sensory,  and  sympa- 
thetic, while  the  filaments  which  leave  the  ganglion  to  supply 
the  various  organs,  are  known  as  the  emergent  branches,  which 
thus  exercise  a  mixed  and  varied  function. 


Dorsal  ganglion  of  sympatlietic  nerve  from  a  Mouse,  a,  b,  Connect- 
ing cords  to  adjacent  ganglia ;  ccc,  EfiFerent  and  spinal  nerve  branches ; 
d,  Ganglionic  cells  ;  e,  Nerve  fibres  crossing  the  ganglion. 

The  sympathetic  nerves  chiefly  supply  the  blood-vessels  (round 
■which  they  twine  in  a  complex  manner),  the  glands,  and  the 
viscera. 

For  the  convenience  of  description,  the  sjanpathetic  system  may 
be  divided  into  five  regions — viz.,  the  cephalic,  cervical,  dorsal 
or  thoracic,  lumbar  or  abdominal,  and  sacral  or  pelvic. 


cephalic  portion  OF  the  sympathetic  system 

The  cephalic  portion   consists  chiefly  of  the  ophthcdmdc  or 
lenticvlar,  sph&no-palatine  or  Meckel's,  and  the  otic  ganglia. 
The   Lenticoxar   ganglion    is    situated    between  the   optic 


516 


NEUROLOGY. 


nerve  and  the  inferior  oblique  muscle  of  the  eye,  in  close  contact, 
with  the  motor  oculi  nerve  and  the  ophthalmic  artery.  Its  motor 
root  is  furnished  by  the  third  pair,  and  its  sensory  is  derived 
from  the  palpebro-nasal.  It  also  communicates  with  the  superior 
cervical  ganglion.  Its  emergent  branches  are  the  ciliary  nerves, 
which  accompany  the  ciliary  arteries,  and  supply  the  tunics  of 
the  eyeball 

Meckel's  ganglion,  much  larger  than  the  ophthalmic,  is 
situated  between  the  orbital  and  maxillary  hiatuses,  in  close 
contact  with  the  superior  maxillary  division  of  the  fifth  pair. 
Its  motor  root  is  formed  by  the  Vidian  nerve,  by  which  it  is  also 
connected  with  the  superior  cervical  ganglion,  and  its  sensory 
roots  are  derived  from  the  spheno-palatine  nerve.  Its  emergent 
branches  are  numerous,  and  are  sent  to  the  muscles  and  vessels 
of  the  orbit,  to  the  soft  and  hard  palate,  to  the  nose,  and  to  the 
superior  cervical  and  ophthalmic  ganglia. 

The  One  ganglion  (Arnold's)  is  inconstant ;  it  is  connected 
with  the  inferior  maxillary  division  of  the  fifth  pair,  under  the 
guttural  pouch  and  close  to  the  Eustachian  tube  ;  its  sensory 
root  is  derived  from  the  buccal  nerve,  and  its  motor  from  the 
small  superficial  petrosal.  It  also  communicates  with  the  superior 
cervical  ganglion.  Its  emergent  branches  are  to  the  muscles  of 
the  middle  ear,  to  the  Eustachian  tube,  and  to  the  pterj'goid  and 
tensor  palati  muscles. 


cervical  portion  of  the  sympathetic  system. 

The  cervical  portion  of  the  sympathetic  chain  is  formed  of  two- 
large  ganglia,  connected  by  an  intermediate  cord,  and  placed  one 
at  the  superior,  and  the  other  at  the  inferior  extremity  of  the 
neck. 

The  Superior  Cervical  or  Guttural  ganglion  is  a  long, 
fusiform  body  in  close  connection  with  the  internal  carotid  arter}', 
and  included  with  it  in  a  fold  of  the  membrane  of  the  guttural 
pouch  ;  it  is  situated  in  front  of  the  wing  of  the  atlas,  and  in 
close  proximity  to  the  ninth,  tenth,  eleventh,  and  twelfth  cranial, 
and  first  cervical  nerves,  from  all  of  which  it  receives  branches. 
These  filaments  form  a  plexus  round  the  ganglion,  known  as  the 
guttural  plexus.  The  emergent  branches  of  the  superior  cervical 
ganglion  are  divided  into  three  orders — viz.,  1st,  Those  accom- 
panying the  internal   carotid  into  the  cranium  ;   Ivcl,   A   large- 


CERVICAL    PORTION    OF    THE    SYMPATHEITC    SYSTEM!,         517 

"bundle,  which  gains  the  origin  of  the  three  terminal  divisions  of 
the  primitive  carotid ;  and  Srd,  Small  filaments  supplying  the 
.guttural  pouch  and  pharynx. 

1.  The  branches  which  accompany  the  carotid,  generally  two 
in  number,  the  anterior  being  largest,  wimd  round  the  artery,  and 
anastomose  one  with  the  other.  Extending  to  the  cavernous  sinus, 
they  form  the  cavernous  plexus,  by  which  they  communicate  with 
many  of  the  cranial  nerves,  and  send  filaments  to  join  analogous 
filaments  from  the  opposite  side,  A  branch  from  this  plexus  joins 
the  superficial  petrosal  nerve,  and  contributes  to  the  formation 
of  the  Vidian  nerve,  which  joins  the  spheno-palatine  ganglion. 


Fig.  195. 
Thorax  opened  from  tbe  left  side  to  s'low  the  nerves.  1,  Heart ;  2,  Anterior  aorta  ;  3,  Posterior 
aorta ;  4  4,  Trachea ;  5  5,  (Esophag^is ;  6,  Seventh,  7,  Eighth  cervical  nerves ;  8,  First  dorsal 
nerve ;  9  9,  Diaphragm ;  a.  Point  of  (.eparation  of  sympathetic  and  pneumogastric ;  6,  Pneumo- 
gastric  ;  c  c,  Recurrent  :  d,  Cwd'ac ;  e,  Superior,  /,  Inferior  branch  of  the  pneumogastric ;  g  g  g. 
Phrenic ;  g*  g",  Its  rootc,  fron  the  sir.th  and  seventh  cervicals ;  ft,  End  of  cervical  portion  cf 
sympathetic  cord ;  i,  Inferior  corvical  ganglion ;  k,  First  dorsal  ganglion  -.III,  Thorado  part  of 
sympathetic  cord  ;  m  w,  U aicn  of  sympathetic  and  dorsal  nerves ;  n,  Continnation  of  syn^iatlietic : 
o,  Splanchnic. 

In  company  with  fibres  firora  the  ophthalmic  branch  of  the  fifth, 
it  communicates  with  the  ophthalmic  ganglion,  and  also  sends  a 
filament  to  the'  Gasserian  ganglion,  and  mingles  its  fibres  with 
those  of  the  third,  fourth,  and  sixth  cranial  nerves,  or  motor  nerves' 
of  the  eye. 


518  NEUKOLOGY. 

2.  The  fasciculi  joining  the  primitive  carotid  leave  the  inferior 
part  of  the  ganglion  in  numerous  branches,  united  by  communi- 
cating filaments ;  at  the  division  of  the  artery,  they  anastomose 
with  branches  from  the  glosso-pharyngeal  and  pneumogastric, 
forming  the  carotid  plexus,  the  ramifications  of  which  are  almost 
exclusively  distributed  to  the  external  carotid  artery  and  salivary 
glands,  one  twig  being  sent  to  the  otic  ganghon, 

3.  The  guttural  or  pharyngeal  are  very  delicate  branches;  which 
leave  the  anterior  border  of  the  ganglion,  and,  gaining  the 
superior  walls  of  the  pharynx,  communicate  with  filaments 
from  the  glosso-pharyngeal  and  pneumogastric  nerves  to  form 
the  pharyngeal  jjlexus. 

The  intei^mediate  cord  of  the  cervical  gavglia  leaves  tbe 
inferior  part  of  the  ganglion,  and  passes  down  the  neck  in  com- 
pany with  the  par  vagum  to  the  entrance  of  the  thorax,  where 
it  joins  the  inferior  ganglion. 

The  Interior  Cervical  ganglion,  larger  than  the  superior, 
is  placed  on  the  inner  side  of  the  costal  insertion  of  the  scalenus 
muscle,  and  against  the  trachea,  the  right  ganglion  being  always 
a  little  in  advance  of  the  left,  which  is  separated  from  the  trachea 
by  the  oesophagus.  The  form  of  this  ganglion  is  variable  and 
irregular,  sometimes  being  lenticular  and  sometimes  elongated, 
but  always  more  or  less  radiated.  Occasionally  it  is  double  ;  in 
this  case,  which  occurs  inore  generaDy  in  the  right  than  in  the 
left  ganglion,  the  two  portions  are  distinguished  as  anterior  and 
•posterior;  the  former,  which  is  the  smaller,  being  the  middle 
cervical  ganglion  of  the  human  anatomist,  the  two  being  joined 
by  a  short  band  of  grey  matter. 

This  ganglion  receives  two  branches  from  the  cervical  nerves, 
one  being  formed  by  filaments  which  emanate  from  the  second 
to  the  seventh  pairs,  inclusive,  the  other  being  a  single  branch 
from  the  eighth.  In  addition  to  these,  several  filaments  are 
transmitted  to  it  from  the  pneumogastric. 

The  emergent  branches,  detached  from  the  inferior  and  poste- 
rior parts  of  the  ganglion,  chiefly  supply  the  heart,  some  filaments 
being  sent  to  the  anterior  mediastinum  and  the  arteries  of  the 
brachial  trunk. 

The  Cardiac  nerves  are  five  in  number,  three  coming  from 
the  left  and  two  from  the  right  cervical  ganglion  ;  these,  assisted 
by  branches  from  the  vagus,  form  the  cardiac  plexus,  some 
branches  from  which  accompany  the  aorta,  and  are  distributed 


THORACIC    PORTIOM    OF    THE    SYMPATHETIC    SYSTEM.         519 

to  the  tissue  of  the  ventricles  and  auricles  ;  some  follow  the 
divisions  of  the  pulmonary  artery,  and  assist  in  the  formation  of 
the  bronchial  plexus ;  and  others,  following  the  brachial  arteries 
and  trachea,  form,  on  the  inferior  face  of  the  latter,  a  very  large 
fasciculus  known  as  the  tracheal  plexus.  This  plexus  is  traversed 
by  the  two  recurrent  nerves,  which  give  and  receive  numerous 
filaments  as  they  pass. 


flc;.  196. 
Abdominal  portion  of  sympathetic  nerves-viewed  from  the  left  side.  11,  Posterior  aorta ; 
2,  Liver;  3,  Scomach  ;  4.  Spleen;  5.  Anterior  mesenteric  nerves :  5' 5',  SmaU  iL.e.stme  6  Left 
kidney;  7.  Small  mesenteric  nerves;  7',  Floating  colon  :  a  a,  Sympathetic  cord ;  a  «.  Union  of 
Bympathe tic  and  lumbar  nerves;  a"  a",  Branches  joining  sympathetic  -"^  Postenor  mesen  er  c 
plexL ;  b,  Great  splanchnic ;  c,  Semilunar^anglion  ;  d.  Hepatic  plex.^ ;  e  Gastnc  P'«^  '/■  ^^^^"'^ 
plexus;  g.  Anterior  mesenteric  plexus;  h,  Left  renal  plexus;  i,  Posterior  mesenteric  plexus  . 
k.  Left  spermatic'plexus. 

THORACIC  PORTION  OF  THE  SYMPATHETIC  SYSTEM. 
The  cord  which  represents  the  dorsal  portion  of  the  sympathetic 
chain  extends  from  the  inferior  cervical  ganglion  to  the  diaphragm, 
crossing  the  intercostal  arteries,  and  passing  under  the  vertebro- 
costal articulations,  against  which  it  is  tixed  by  the  pleura. 
Passing  through  the  arch  at  the  superior  border  of  the  diaphragm. 


520  NEUROLOGY. 

"by  the  side  of  the  psoas  parvus  muscle,  it  is  continued  in  the 
abdominal  cavity  by  the  lumbar  portion.  During  its  passage 
through  the  thorax,  seventeen  small  fusiform  ganglia,  one  at  each 
intercostal  space,  present  themselves.  The  afferent  branches,  from 
one  to  three  generally,  are  furnished  by  the  inferior  branches  of  the 
dorsal  nerves,  which  pass  through  the  intervertebral  foramina  to 
each  ganglion.  The  emergent  branches  are  some  small  fibres 
which  supply  the  pleura,  and  the  large  and  small  splanchnic  nerves. 

The  Great  Splanchnic  nerve  is  detached  from  the  sixth  or 
seventh  ganglion,  and  receives,  in  its  backward  course,  additional 
fibres  from  all  the  other  ganglia  except  the  last  two  or  three.  It 
enters  the  abdominal  cavity  in  company  with  the  psoe  muscles, 
Avhen  it  presents  a  small  ganglionic  mass,  and  is  then  bent 
inwards,  and  terminates  in  a  large  ganglion,  the  semilunar  or 
solar  ganglion,  between  the  coeliac  axis  and  the  anterior  mesen- 
teric trunk. 

The  Semilunar  ganglia,  the  largest  of  all  the  sympathetic 
ganglia,  are  elongated  from  before  backwards,  and  flattened  from 
above  downwards.  They  communicate  by  means  of  a  large  and 
fstrong  grey  cord,  which  passes  behind  the  mesenteric  trunk,  and 
by  a  number  of  filaments  which  proceed  from  side  to  side  in 
front  of  this  artery.  On  the  inferior  face  of  the  aorta  these 
filaments  form  the  solar  plexus,  which  receives  branches  from  the 
superior  cord  of  the  par  vagum,  and  is  divided  at  its  periphery 
into  numerous  secondary  plexuses,  from  which  many  ramifications 
interlace  and  anastomose  in  a  very  complex  manner  round  the 
divisions  of  the  arteries,  which  they  accompany  into  the  neigh- 
bouring organs. 

Of  these  secondary  plexuses,  the  gastric  distributes  its  branches 
to  the  stomach,  on  the  walls  of  which  they  anastomose  with  the 
jmeumogastric  nerve  ;  the  heixdic  supplies  the  liver,  duodenum, 
pylorus,  and  pancreas  ;  the  splenic,  the  sj)leen  and  part  of  the 
stom-ach  ;  the  anterior  mesenteric,  the  largest  of  all,  the  viscera, 
supplied  by  the  anterior  mesenteric  artery ;  and  the  renal  and 
suprarenal,  double  and  less  distinct  than  the  others,  supply  the 
kidneys  and  suprarenal  capsules. 

The  numerous  strong  branches  which  leave  the  solar  plexus, 
behind  the  anterior  mesenteric  artery,  and  run  along  the  inferior 
face  of  the  aorta,  frequentlj^  anastomosing  with  each  other,  form 
the  lumho-dortia  plexus,  which  unites  with  the  posterior  mesen- 
teric plexus. 


SACBAL    PORTION    OF    THE    SYMPATHETIC    SYSTEM.  521 

The  Lesser  Splanchnic  nerve  is  formed  by  filaments  from 
the  last  two  or  three  dorsal  ganglia,  which  instead  of  imiting 
with  the  great  splanchnic,  are  sent  direct  to  the  solar  plexus,  and 
are  confounded  with  the  nerves  of  the  kidneys  and  suprarenal 
plexus. 

LUMBAR   PORTION    OF    THE    SYMPATHETIC    SYSTEM. 

The  lumbar  or  abdominal  portion  of  the  S3niipathetic  chain  is 
a  continuation  of  the  dorsal,  and  like  it,  has  fusiform  ganglia  at 
each  lumbar  nerv«.  It  rests  against  the  psoas  parvus  muscle, 
near  the  inferior  common  vertebral  ligament,  and  is  covered,  on 
the  left,  by  the  aorta,  and  on  the  right,  by  the  posterior  vena 
cava.  It  is  directly  continuous  with  the  sacral  portion  at  the 
sacro-limibar  articulation. 

The  afferent  branches  to  the  lumbar  ganglia  are  furmshed  by 
the  inferior  branches  of  the  lumbar  nerves;  the  emergent  branches, 
analogous  to  those  which  form  the  splanchnic  nerves,  are  not 
constant  in  number,  but  are  generally  fewer  than  the  ganglia- 
Two  or  three  of  them  unite  with  the  lumbo-aortic  plexus,  sad 
the  others,  gaining  the  origin  of  the  posterior  mesenteric  artery, 
and  anastomosing  with  the  posterior  branches  of  the  lumbo-aortic 
form  the  posterior  mesenteric  plexus,  which  contains  a  ganglion 
more  or  less  voluminous,  in  its  centre.  The  ramifications  of  this 
plexus  accompany  the  different  branches  of  the  posterior  mesen- 
teric artery,  to  be  distributed  to  the  floating  colon  and  rectum  ; 
and  two  or  three  large  branches  join  the  anterior  mesenteric 
plexus,  after  sending  a  few  small  divisions  to  the  colic  mesentery. 
Branches  from  it  also  surround  and  accompany  the  spermatic 
arteries,  constituting  the  speiwiatic  plexus  ;  and  lastly,  two  other 
long  divisions  enter  the  pelvis  on  each  side,  and  being  distributed 
over  the  external  surface  of  the  peritoneum,  gain  the  side  of  the 
rectum,  where  they  meet  filaments  wliich  emanate  directly  from 
the  sacral  nerves.  The  anastomosis  of  these  divisions  results  in 
a  rich  nervous  network,  the  pelvic  or  hypo-gastric  plexus,  which 
supplies  the  organs  contained  within  the  pelvis. 

SACRAL    PORTION    OF    THE    SYMPATHETIC    SYSTEM. 

The  sacral  or  pelvic  portion  of  the  sympathetic  is  the  continu- 
ation of  the  lumbar,  and  is  situated  under  the  sacrum,  and  to  the 
inner  side  of  the  sacral  nerves.      It  presents  four  ganglia,  which 


522  COMPAEATIYE  NEUrOLOGY. 

commimicate  with  these  nerves  by  numerous  filaments,  and  give^ 
ofif  several  small  twigs,  which  are  lost  in  the  cellular  tissue  on  thfr 
inferior  face  of  the  sacrum. 

The  terminatior^  of  the  symjJathetic  nerve  is  not  always  the 
same,  and  while  it  often  ends  in  a  delicate  filament,  which  is 
carried  under  the  middle  coccygeal  artery,  and  unites  with 
that  of  the  opposite  side,  it  sometimes  terminates  in  a  filament 
which  communicates  with  the  last  pair  of  sacral  nerves. 


COMPARATIVE  NEUROLOOY. 

RUMINANTIA. 

NoTWiTHSTANDn^G  the  greater  development  of  the  coccyx  in  the  ox,  the 
spinal  cord  is  not  prolonged  further  backwards  than  in  the  horse  ;  nor  is  it 
60  in  any  of  the  animals  which  engage  our  attention,  with  the  exception  of 
the  rabbit  and  bird. 

The  optic  nerves  and  pituitary  gland  are  larger,  and  the  testes  more  separated 
from  the  nates  than  in  the  horse.  The  cerebral  convolutions  are  fewer  in  number 
but  larger,  while  ths  hemispheres  themselves  are  larger  posteriorly.  Withrespcct 
to  the  cranial  nerves  the  dififerences  are  not,  as  a  rule,  of  sufl&cient  importance 
to  claim  notice  here.  We  may,  however,  note  that  the  jugular  ganglion  and 
pharyngeal  branch  of  the  tenth  nerve  both  are  very  large.  The  recurrznt 
nerves  are  separated  from  the  pneumogastric  trunk  and  carotid  artery  by  the 
brcarlth  of  the  oesophagus  ;  the  latter  organ  is  more  amply  supplied  with  nerves 
than  that  of  the  horse.  The  superior  oesophageal  branch  chiefly  supplies  the 
rumen,  the  inferior  the  other  compartments.  The  spinal  accessory  divides  into 
l-wo  branches,  superior  and  inferior,  the  latter  supplying  the  muscles  of  the 
infero-lateral  cervical  region. 

The  radial  nerve  sends  two  cutaneous  branches  downv.'ards,  one  of  which 
becomes  lost  at  the  carpus,  v/hile  the  other,  becoming  more  anterior,  descends 
the  metacarpus,  and  supplies  the  dorsal  nerves  of  the  digits.  The  median  and 
cubital  nerves  are  not  connected  at  the  carpus,  but  continued  downwards,  the 
former  as  the  internal,  the  latter  as  the  external  metacarpal  nerve,  each  supply- 
ing its  respective  digit ;  about  the  distal  end  of  the  metacarpus,  a  branch  from 
the  internal  passes  across  to  join  the  external  nerve,  whUe  lower  down  a  second 
branch  from  the  internal  nerve  forms  the  external  collateral  nerve  of  the  inner 
digit,  and  still  lower  a  third  branch  from  the  same  source  forms  the  internal 
collateral  nerve  common  to  both  the  digits. 

In  the  nerves  of  the  lumbo-sacral  plexus  there  is  little  to  note  of  importance. 
The  dorsal  nerves  of  the  digits  are  given  off  by  the  musculo-cutaneous  nerve. 
The  anterior  tibial  nerve  sends  a  branch  down  the  anterior  groove  in  the- 
metatarsus ;  it  divides  in  the  distal  notch  to  form  the  posterior  deep  digital 
nerves.  There  is  no  connecting  branch  between  the  external  and  internal 
metatarsal  nerves, 


CARNIVORA. 


OMNIVORA. 


523 


In  the  hog  the  cerebral  convolutions  are  still  fewer  than  in  the  ruminant, 
Taut  beyond  this  fact,  the  brain  presents  no  important  comparative  features. 
The  superior  mamillary  division  of  the  fifth  nerve  pursues  a  remarkably  short 
course  in  the  orbital  fossa.  The  pneumogastric  nerve  unites  in  the  cervical 
region  with  the  sympathetic  ;  its  oesophageal  portions  differ  chiefly  in  the 
superior  branch  being  very  much  larger  than  the  inferior. 

The  nerves  of  the  brachial  plexus  p-esent  few  deviations  from  the  type,  with 
the  exception  of  the  median  and  cvMtal  nerves.  The  former  of  these,  below 
the  carpus,  supplies  the  interosseous  palmar  muscles,  and  afterwards  "divides 
into  four  branches,  one  for  each  of  the  four  digits  ;  those  supplying  the  large 
digits  reach  the  central  interdigital  space.  The  cubital  nerve  bifurcates  near 
the  trapezium,  one  branch  running  down  the  flexor  tendons  externally,  to 
supply  the  outer  digit,  the  other  gains  the  anterior  aspect  of  the  metacarpus, 
and  furnishes  the  dorsal  nerves  of  the  external  digits. 

In  the  lumbo-sacral  plexus  we  note  that  the  musculo-ctiianeous  nerve  on 
reaching  the  metatarsus  trifurcates,  thus  forming  the  dorsal  nerves  of  the 
digits.  The  anterior  tibial  nerve  passes  down  between  the  large  metatarsal 
bones,  and  communicates  with  the  plantar  nerves,  the  external  of  which 
supplies  the  outer  and  partly  the  inner  digits,  the  internal  nerve  being  small. 

CAENIVORA. 

In  the  brain  of  camivora  the  nates  are  smaller  than  the  testes,  and  the 
olivary  bodies  well  marked.  The  olfactory  lobes  are  exceedingly  weU  deve- 
loped, the  sense  of  sraell  attaining,  perhaps,  its  maximrni  of  acuteness  in  these 
animEils.     The  fourth  ventricle  is  large  and  deep. 

A  branch  of  the  seventh  nerve  accompanies  the  duct  of  Steno  to  the  facial 
region.  The  pneumogastric  and  sympathetic  trunks  are  inseparably  united 
in  the  cervical  region.  The  recurrent  nerves  arise  by  two  branches  which 
eupply  sparingly  the  trachea  and  oesophagus,  these'  organs  being  also  supplied 
by  the  tracheo-oisophageal  branch  of  the  superior  laryngeal  nerve.  The 
oesophageal  plexus  of  the  pneumogastric  is  better  marked  than  in  the  horse. 
The  bronchial  nerves  are  nimierous  and  large. 

In  the  dog,  the  nerves  of  the  brachial  plexus  as  far  as  the  carpal  region 
resemble  in  the  main  those  of  the  horse.  The  dorsal  nerves  of  the  digits  are 
supplied  by  a  cutaneous  branch  of  the  radial  nerve.  The  median  nerve  is 
attached  superiorly  to  the  cubital  Inferiorly  it  inclines  to  the  inner  aspect  of 
the  Umb,  and  below  the  carpus  it  divides  into  six  branches,  one  of  which 
crosses  over  to  unifp  wilh  a  branch  of  the  cubital,  and  form  the  superfixjial 
•palmar  arch.  The  remaining  palmar  branches  supply  aU  the  digits  excepting 
the  fourth  and  part  of  the  third.  The  cubital  nerve  divides  into  a  dorsal  and 
a  palmar  branch ;  the  first  running  down  the  forearm  and  carpus  externally 
to  supply  the  fourth  digit ;  the  latter  divides  into  eight  branches,  which,  deep- 
seated,  supply  all  the  digits  excepting  part  of  the  index  or  first,  a  branch 
passing  across  to  the  pollex,  and  forming  what  may  be  regarded  as  a  deep 
palmar  arch. 


524  COMPARATIVE  NEUROLOGY. 

£n  the  posterior  limb  the  dorsal  nerves  of  the  digits  are  formed  by  the  thxes 
terminal  branches  of  the  musciQo-cutaneous  nerve.  The  external  and  internal 
plantar  nerves  supply  digital  branches,  the  former  to  aU  the  digits  except  the 
internal  branch  of  the  fourth. 

RODENTIA. 

The  brain  of  the  rabbit  is  more  lowly  organised  than  that  of  any  other 
domesticated  mammal.  The  convolutions  cannot  be  said  reall}'  to  exist ;  and 
the  Sylvian  fissure  is  merely  indicated.  No  portion  of  the  cerebellum  is 
covered  by  the  cerebrum  when  in  situ.  The  olfactory  lobes  are  very  large, 
and  the  testes  are  smaller  than  the  nates. 

Although  in  this  animal  the  tail  is  very  short,  the  spinal  cord  extends  bej-ond 
tlie  sacnmi.  A  singular  nerve  is  foi'med  by  .a  branch  from  the  superior  laryn- 
geal, and  usually  one  from  the  pneumogastric,  and  proceeds  down  the  nect 
with  the  sympathetic  trunk,  entering  the  thorax  to  reach  the  substance  of  the 
heart ;  it  receives  twigs  from  the  first  thoracic  ganglion.  The  name  "depressor 
nerve  of  the  circulation"  has  been  given  'to  this  nerve  by  its  discoverers, 
MM.  Cyon. 

AVES. 

In  the  nervous  system  of  birds  the  chief  point  of  interest  is  the  brain,  which 
is  less  highly  organised  than  that  of  the  mammalia.  The  cerebrum  is  pointed  an- 
teriorly, the  heniispheres  being  separated  by  a  shallow  longitudinal  fissure. 
There  is  a  very  slight  indication  of  the  fissure  of  Sylvius,  but  the  convolutions, 
corpus  callosum,  and  septum  lucidum  are  absent.  Two  rounded  bodies,  the 
optic  lobes,  occupy  the  position  of  the  mammalian  greater  lobes.  The  lateral 
lobes  of  the  cerebellum  are  very  rudimentary,  and  the  pons  Varolii  is  wanting. 

The  cranial  nerves  are,  in  number,  twelve  pairs,  and  they  resemble  those  of 
the  mammal  in  their  origins,  and,  in  a  general  sense,  in  their  distribution 
-also. 

In  birds  the  spinal  cord  extends  into  the  coccygeal  region.  The  nerves  cf 
the  brachial  plexus  are  divisible  in  the  Vving  into  two  groups ;  a  posterior 
■which  represents  the  brachial,  internal  cutaneous,  and  radial;  and  an  anterior 
representing  the  cubital,  median,  and  musculo-cutaneous. 

The  lumbo-sacral  pleLius  likewi'-.e  consists  of  two  portions,  the  anterior 
supplying  the  fascia  Ida,  crural,  internal  saphenic,  and  obturator  nerves ; 
-irhile  the  posterior  gives  off  the  gluteal,  great  sciatic,  and  popliteal  nerves. 


CHAPTER  VII 

^STHESIOLOGfY. 

This  section  of  the  subject  deals  with  the  organs  of  sensation. 
When  sensation  is  peculiar  to  a  certain  organ,  and  received 
therein  by  the  medium  of  a  complex  anatomical  mechanism,  it  is 
known  as  sensation  of  the  higher  order,  or  special  sense ;  the 
special  senses  are  hearing,  siglit,  smell,  and  taste,  localised  re- 
spectively in  the  ear,  the  eye,  the  nose,  and  the  tongue. 

On  the  other  hand,  when  the  organs  of  sensation  merely  trans- 
mit the  impressions  of  pleasure  and  pain,  such  impressions  are 
termed  common  sensation  ;  and  sensitiveness  to  such  is  shared  by 
nearly  all  parts  of  the  body,  though  in  a  much  greater  degree  in 
some  than  in  others. 

Portions  of  the  surface  of  the  body  which  are  more  sensitive 
than  the  rest,  and  prominent,  are  known  as  the  organs  of  touch, 
such  as  the  end  of  the  finger  in  man,  the  nose  in  the  horse,  &c. 
The  skin  being  a  very  sensitive  structure,  we  place  it  and  its 
appendages  under  the  heading  of  organs  of  common  sensation. 

We  describe  first  the  organs  of  special  sense,  then  those  of 
common  sensation. 

The  Eae. 

The  apparatus  of  hearing  is  composed  of  three  parts — the 
external,  middle,  and  internal  ear ;  the  two  first  being  accessoiy, 
for  the  collection  and  transmission  of  sounds,  and  the  latter  the 
essential  organ  which  receives  the  impressions  thus  conveyed. 


EXTEENAL    EAR. 

The  external  ear  consists  of  the  concha,  or  projecting  shell-like 
orifice,  and  the  meatus  auditoriviS  externus,  or  passage  which 

525 


526 


iESTHESIOLOGY. 


extends  from  the  base  of  the  concha  to  the  tympanic  membrane 
bounding  the  cavity.  It  is  partly  osseous 
and  partly  cartilaginous,  and  is  narrower  in 
the  middle  than  at  either  extremity.  Jts 
lining  is  a  continuation  of  the  skin  of  the 
concha,  and  it  graduaUy  becomes  thinner  as 
it  descends  ;  it  is  perforated  by  numerouii 
small  openings  from  the  ceruminous  glands, 
which  secrete  the  wax  of  the  ear.  The 
cartilages  of  the  external  ear  are  the  conchal, 
the  annulcir,  and  the  acwtifoimi. 

The  conchal  cartilage  has  some  cnaracter- 
istic  feature,  in  shape  or  size,  in  most  classes 
of  animals  ;  in  the  horse  it  is  a  conical  tube, 
with  the  narrow  end  downwards,  and  having  a 
perpendicular  aperture  directed  forwards  when 
the  ear  is  ' '  set ;  "  it  terminates  superiorly  in 
a  point  on    the    posterior  border.      Inferiorly 
it  is  attached  to  the  annular  or  ring-shaped 
cartilage,  which  surrounds  and  is  attached  to 
the  bony  meatus.      The  scutiform  cartilage  is 
an  irregularly  triangular  plate,  partly  covering 
the  temporalis  muscle,  and  attached  by  muscles 
to   the  conchal  cartilage   and   to   the 
bones  of  the  skull ;  it  appears  to  act 
as  a  kind    of   lever    in    moving   the 
concha,  the  mobility  of  which  struc- 
jFiG.  198.  ture  is  so  great  in  the  solipede,  that 

JCrilSriu?,,^:;^     J'    i=   «g^«J.    "<>«    mappropriately, 

^  anterior  angle ;  d,    Supero-posterior       aS    the    chief    OTQOiTi    of    eXJOTCSStOTh    in 
'angle;  e,  Anterior  border;  /,  Poste-        +1,    f         '1 
rior  border  ;  3,  Snperkurborder.  tliat  animaL 


Fio.  197. 

Eight  conchal  and  an- 
Bular  cartilages.  1,  Con- 
chal cartilage;  a.Sttperior 
extremity  ;  6,  Inferior 
extremity  ;  c,  Outer  sur- 
face ;  d,  Inner  surface  : 
e.  External  border;  /,  In- 
ternal border;  2,  Annu- 
lar cartilage  ;  g,  Anterior 
surface  ;  h,  Superior;  and 
i,  Inferior  border. 


MIDDLE    EAR. 

The  middle  ear  or  tympanum  is  an  irregular  bony  cavity  within 
the  petrosal  bone.      It  is  bounded  externally  by  the  membrana 

rpani  or  drum  of  the  ear ;  internally  by  the  bony  walls  of 
internal  ear ;    anteriorly  by  the  Eustachian  tube ;   and  pos- 
teriorly by  the  mastoid  cells. 

The  Membrana  tympant  is  a  semi-transparent,  nearly  circular 
membrane,  vsdth  its  middle  drawn  inwards.      It  is  inserted  to  a 


MIDDLE    EAU.  527 

groove  round  the  inner  end  of  the  external  meatus,  and  is  com- 
posed of  three  layers  ;  an  ext&i-nal,  or  epidermic,  a  prolongation 
of  the  skrn  lining  th«  meatus  ;  a  middle,  or  fibrous,  the  fibres 
being  in  two  sets,  one  radiating  from  the  centre  to  the  circum- 
ference, the  other  scattered  and  indistinct,  except  near  the 
periphery,  where  they  form  a  dense  ring  ;  and 
an  intermal,  or  mucous,  derived  from  the 
mucous  lining  of  the  middle  ^r. 

A  chain  of  small  bones,  the  auditory  ossicles 
(ossicula  auditus)  stretch  across  the  tympanum. 
Thev  are  the  malleus,  incus,  stapes,  and  len-        ^      ,?'        tt  j 

J  J  >  r    -J  The  malleus,  a,  Head; 

ticular  bone,  or  os  orbiculare.  6,  Neck ;    c.  Handle ; 

The  Malleus,  or  Hammer,  presents  a  '^.  ^p«x=«^  8™<^- 
rounded  head  (capituluTn),  a  neck,  a  liandle  (man/iibriu'iirh),  a 
long  and  a  short  process  (processus  gracilis  and  brevis).  The 
head  articulates  with  the  incus ;  the  handle  is  received  between 
the  inner  and  middle  coats  of  the  membrana  tympani  ;  the  long 
process,  in  man,  extends  to  the  Glaserian  fissure  ;  and  the  short 
process,  very  obtuse,  lies  in  contact  with  the  drum. 

The  Incus,  or  Anyil,  which  in  shape  somewhat  resembles  the 
bicuspid  tooth  of  man,  has  a  body  and  two 
crura  or  processes.  The  body  is  concave  on 
its  surface,  and  articulates  with  the  head  of 
the  malleus;  the  short  cms  is  connected  with 
the  posterior  wall  of  the  tympanum  ;  and  the  incus"  "af" Body;  b, 
long  crus  bears  the  os  orbicidare,  a  round  Articuiar^aceforrmd- 
bone,  about  the  size  of  a  grain  of  sand,  at  its  Long  cms;  e,  oa  orwcn- 
extreme  point.  ^®" 

The  Stapes,  or  STnmup,  possesses -a  base,  two  crura,  and  a. 
head.     The  base  is    oval,    and    placed    upon  ± 

the  fenestra  ovalis  ;  the.  crura  converge  irom  ^'Mri 

each  extremity  of  the  base  to  a  constricted  ^»» 

portion  termed  the  neck,  on  which  is  placed  p^^j  ^^ 

the  head,  which  articulates  with  the  os  orbi-        stapes,  a, Head;  6 », 

Culare.  crura ;  c.  Base. 

Th^  inner  wall  of  the  tympanum  is  very  uneven,  and  presents 
several  eminences  and  openings.  The  oval  opening,  near  its 
upper  part,  is  the  fenestra  ovalis,  which  leads  into  the  cavity 
of  the  vestibule.  Above  this  fenestra,  between  it  and  the 
roof,  is  a  ridge  formed  by  the  aqueduct  of  Fallopius,  and 
beneath   is  the  round  opening  of  the   fenestra  rotunda.      The 


Fig.  200. 


528 


lOLOGFY. 


latter  opeoiiig  leads  into  the  cochlea,  and  in  the  recent 
subject  is  closed  by  the  lining  membrane  of  the  cavity ;. 
between  the  two  fenestrse  is  the  projegtion  termed  the  promon- 
tory. At  the  posterior  part  of  the  tympanum,  numerous  open- 
ings lead  into  the  rrmstoid  cells,  which  are  small,  irregular, 
freely-communicating  cavities  in  the  auditory  bulb  of  the  temporal 
bone.  Behind  the  fenestra  ovalis  is  a  conical  eminence,  the 
pyramid,  in  the  apex  of  which  is  a  groove  for  the  tendon  of  the 
stapedius  muscle.  The  anterior  part  of  the  tjanpaaum  narrows 
towards  the  opening  of  two  canals,  separated  from  each  other 
by  a  lamina  of  bpne,  the  processus  cocrdearifonniy ;  the  upper 
and  smaller  of^  these  canals  contains  the  tensor  tympani  muscle, 
and  the  other  leads  into  and  forms 
the  bony  portion  of  the  Eustachian 
tube ;  a  tube  partly  osseous  and 
partly  cartilaginous,  which  extends 
from  the  tympanum  to  the  guttural 
pouch,  and  is  the  passage  tlirough 
which  air  is  supplied  to  the  middle  ear. 
Tlie  Glaserian  fissure  is  immediately 
in  front  of  the  ring  to  which  the 
membrana  tympani  is  inserted. 

Th'^  bones  of  the  middle  ear  are 
united  and  kept  in  their  positions  by 
muscles  and  ligaments.  The  muscles 
are  the  stapedius,  which  has  its  origin 
in^  the  interior  of  the  pyramid,  and  is 
inserted  into  the  neck  of  the  stapes; 
the  tensor  tympani,  which  arises  from 
the  cartilaginous  portion  of  the  Eusta- 
chian tube,  and  surface  of  the  sphenoid,  and  passing  through  a 
small  canal,  becomes  inserted  into  the  handle  of  the  malleus ;  the 
laxator  tympani,  which  arises  from  the  sphenoid,  and  passing 
through  an  opening  in  the  Glaserian  fissure,  is  inserted  into  the 
neck  of  the  malleus.  The  ligaments  are  the  suspensory,  whicli 
attaches  the  head  of  the  malleus  to  the  upper  wall  of  the 
tympanum  ;  the  posterior,  which  attaches  the  short  cms  of  the 
incus  to  the  margin  of  the  mastoid  ceUs ;  and  the  annular, 
which  attaches  the  foot  of  the  stapes  to  the  membrane  closing 
the  fenestra  ovalis. 

The   tympanum   is   lined   by  a   vascular   mucous   membrane. 


Fia.202. 

External  wall  of  the  "tympamun — 
viewed  from  within,  a,  Meatus  audi- 
torius  extemus ;  b,  Tympanic  mem- 
brane ;  c.  Malleus ;  d  d.  Mastoid  cells ; 
e  e,  Outer  boundary,  or  ring  of  tym- 
/,    Orifice   for  Eizstachian 


pamam; 
tube. 


INTERNAL    EAE. 


529 


which  is  continuous,  through  the  Eustachian  tube,  with  that  of 
the  guttural  pouch  and  pharynx,  and  is  reflected  into  the  mastoid 
cells.  The  whole  of  this  membrane  is  lined  with  epithelium, 
that  in  the  tube  being  ciliated. 


INTERNAL  EAR. 

The  internal  ear,  from  its  complexity  termed  the  labyrinth,  is 
the  ultimate  part  of  the  organ  of  hearing.  It  consists  of  a  cavity 
whose  boundaries  include 
an  osseous  outer,  and  a 
membranous  inner  por- 
tion, respectively  termed 
the  hony  and  the  mem- 
branous  labyrinths. 
The  bony  labyrinth  is  an 
irregular  cavity,  divided 
into  three  separate  parts; 
the  vestibule,  semicircu- 
lar canals,  and  cochlea. 

The  Vestibule  is  an 
irregular,  oval  -  shaped 
cavity,  situated  between 
the  cochlea  and  the  semi- 
circular canals,  having 
the  fenestra  ovalis  pene- 
trating its  outer  wall, 
and  the  five  round  open- 
ings of  the  semicircular 
canals  at  its  back.  At 
the  upper  part  of  its 
inner  wall  are  two  de- 
pressions, the  fovea 
elliptica  and  fovea 
hemispherica,  separated 
by  a  ridge,  the  emi- 
nentia  pyramidalis,  all 
of  which  are  pierced  by 
numerous  small  open- 
ings, macula  cribrosa,  for  the  passage  of  nerve  filaments.  •  Behind 
the  fovea  hemispherica  is  the  opening  of  the  aqueduct  of  the 

2  M 


Diagram  of  the  ear. 


In  the  internal  portion,  the  black 
part  shows  the  cavities  of  the  bony,  and  the  white  part  those 
of  the  membranous  labyrinth.  Ovi,  Cavity  of  the  concha  ; 
aG,  External  auditory  meatus;  Tr,  Tympanic  membrane  ; 
Ct,  Tympanum  ;  Ak,  Auditory  ossicles ;.  Fr,  Fenestra 
rotunda ;  ER,  Eustachian  tube ;  L,  Guttural  pouch  ;  Sac, 
Sacculus  ;  ut,  Utricle  ;  oB,  uB,  Bony  ;  Co,  hB,  Membranous 
semicircular  canals  ;  De,  Aquasductus  vsstibuli ;  Se,  Saccus 
endolymphaticus  ;  St,  Scala  tympani ;  Sv,  Scala  vestibuli  ; 
Con,  Scala  intermedia  ;  +,  Its  vestibular  caecal  sac ;  Cr, 
Ductus  reuniens ;  *,  Its  apex  :  Dp,  Aquaeductus  cochleae, 
vel  Cotunnii. 


530  ^STHESIOLOGT. 

vestibule,  which  extends  to  the  posterior  surface  of  the  petrosal 
bone,  and  gives  passa^je  to  a  diverticulum  of  the  membranous 
labyrinth.  At  the  lower  and  anterior  part  of  the  vestibule  is 
the  large  opening,  apertura  scales  vestihuli,  or  vestibular  canal 
cf  the  cochlea. 

The  Semicircular  canals  are  three  half-circular  passages 
communicating  with  the  vestibule,  into  which  they  open  by  both 
extremities,  and  having,  near  one  extremity  of  each,  a  dilatation 
termed  the  ampulla.  These  canals  are  distinguished  as  superior 
or  perpendicular,  posterior  or  oblique,  and  inferior  or  hori- 
zontal. The  anterior  or  dilated  end  of  the  superior  canal  enters 
the  vestibule  by  a  distinct  orifice,  while  its  posterior  or  non- 
dilated  end  joins  'the  anterior  non-dilated  end  of  the  oblique ; 
thus  the  two  enter  the  vestibule  by  one  common  opening,  the 
posterior  end  of  the  oblique  canal  being  dilated,  and  entering  by 
a  distinct  opening.  The  inferior  canal  has  two  openings,  of 
which  the  anterior  is  dilated. 

The  Cochlea,  or  Snail  shell,  is  the  anterior  division  of  the 
labyrinth,  and  the  most  complex  of  the  three.  It  consists  of  a 
gradually  tapering  spiral  canal,  which  takes  two  and  a-half  turns 
round  a  central  axis.  This  axis,  termed  the  modiolus,  is  widest 
at  its  base,  where  it  is  pierced  by  numerous  small  openings, 
through  which  pass  the  filaments  of  the  cochlear  branch  of  the 
auditory  nerve.  The  spiral  canal  is  divided  into  two  compart- 
ments (scalce)  by  a  partition,  partly  bony  and  partly  membranous, 
the  lamina  spiralis,  which  is  wound  spirally  around  the  medio- 
lus  in  the  direction  of  the  canal,  and  terminates,  at  the  apex  of 
the  cochlea,  by  a  hook-shaped  process,  the  hamulus.  The  two 
compartments  are  thus  completely  separated,  except  at  the  apex, 
where  they  communicate  by  means  of  an  opening,  the  helicotrema, 
under  the  hamulus ;  inferiorly,  one  scala  terminates  in  the  vesti- 
bule, it  is  hence  called  the  scala  vestihuli ;  the  other  leads  to 
the  tympanum  at  the  fenestra  rotunda,  and  is  called  the  scala 
tympani. 

The  whole  of  the  bony  labyrinth  is  lined  by  a  thin  fibro- 
serous  membrane,  which  closes  the  openings  of  both  the  fenestra 
rotunda,' and  fenestra  ovalis,  and,  adhering  to  the  bone,  acts  the 
part  of  a  periosteum.  The  inner  surface  of  this  membrane  is 
smooth,  and  secretes  a  thin  limpid  fluid,  the  perilymph  or  liquor 
Cotunnii,  which  entirely  fills  the  cochlea,  and  in  the  canals  and 
vestibule,  separates  the  bony  from  the  membranous  labyrinth. 


INTERNAL    EAR. 


531 


Fi.i.   204. 

Membranous  labyrinth.     C,  Ductus  cochleari.«  : 

K,  Its  cochlear  blind  end,  and  F,  Its  vestibular 

blind  end  ;   Cr,  Ductus  reuniens  ;   6',   facculus : 

U,  Utricle  ;  R,  Aquseductus  vestibuli. 


The  Membranous  labyrinth,  though  smaller  in  size,  is  nearly 
the  counterpart  in  form  of  the  vestibule  and  semicircular  canals, 
and  consists  of  two  sacks  within  the  vestibule,  the  larger  of  which, 
the  utricle  or  sacculus  communis,  is  elongated  and  lodged  in  the 
fovea  elliptica  ;  the  smaller,  the  sacculus  or  sacculus  proprius,  is 
round,  and  lodged  in  the  fovea  hemispherica.  The  semicircular 
canals,  which  are  about  one-third  the  size  of  the  bony  canals, 
open  by  five  orifices  into  the 
sacculus  communis.  The  sac- 
culus and  utricle  are  united 
by  an  angular  duct,  which 
also  leads  to  the  aqueduct  of 
the  vestibule,  a  canal  termi- 
nating in  a  blind  dilatation, 
the  saccus  endolymphaticus. 
The  bony  lamina  spiralis  being 
incomplete,  the  division  is 
completed  by  two  membranes, 
the  membrane  of  Reissner  and 
the  basilar  membrane,  between 
which  is  the  scala  intermeclia 

or  ductus  cochlearis,  a  tube  which  thus  follows  the  turns  of  the 
cochlea,  originating  at  its  apex  in  a  blind  extremity,  and  terminate 
ing  in  a  tube,  the  ductus  reuniens,  which  unites  it  to  the  sacculus. 
This  labyrinth  is  filled  by  a  limpid  fluid,  termed  the  endolympli 
•or  liquor  Scarpce,  and  is  constructed  of  four  coats ;  an  external 
serous,  a  vascular,  a  nervous,  and  an  inner  serous,  from  which  the 
endolympli  is  secreted. 

Within  the  sacculi  are  small,  rounded,  calcareous  bodies,  the 
<jto-coni(B,  which  consists  of  particles  of  carbonate  and  phosTahate 
of  lime,  held  together  by  animal  matter ;  these  oto-conias  are 
suspended  from  the  membrane,  and  float  freely  in  the  endolymph. 

The  Meatus  auditorius  internus  is  a  bony  canal,  which 
leads  from  the  cranial  cavity  to  the  vestibule,  and  terminates  in 
the  cribriform  plate  of  the  fovea  hemispherica  and  emiuentia 
pyramidalis. 

The  Guttural  Pouches. — The  mucous  membrane,  projecting 
through  a  slit  in  the  inferior  extremity  of  the  Eustachian  tube, 
becomes  dilated  into  a  large  sac,  the  guttural  pouch,  which  is 
peculiar  to  the  solipede  and  the  Hyrax.  These  pouches,  which 
meet  in  the  middle  line,  are  irregular  in  form,  are  related  above 


532 


^STHESIOLOGY. 


with  the  base  of  the  srphenoid  and  occipital  bones,  descending  to 
the  sides  of  the  pharynx  and  larynx,  where  they  terminate  iu  a 
cul-de-sac ;  they  likewise  extend  from  the  inferior  extremity  of 
the  parotid  gland  to  the  anterior  face  of  the  atlas.  For  the 
auricular  muscles,  see  p.  174. 


The  Eye. 

The  apparatus  of  vision  comprises  tbe  essential  organ,  the  globe 

of  the  eye  or  eyeball,  and 
its  accessory  parts  or  append- 
ages. 

The  Globe  of  the  Eye  is 
spherical  in  form,  having  the 
segment  of  a  smaller  sphere 
engrafted  upon  its  anterior 
surface,  and  increasing  its 
antero-posterior  diameter.  It 
consists  of  a  membranous 
sac,  containing  certain  trans- 
parent humours,  of  different 
densities,  which  serve  as  re- 
fracting media  ;  it  is  attached 
to  the  orbit  by  tbe  muscles 
which  move  it,  and  reposes  on 
a  cushion  of  fat,  which  not 
only  maintains  it  in  its  proper 
position,  but  also  assists  ia 
steadying  its  movements. 


Fio.  205. 

■  Diagratnatic  horizontal  section  of  horse's  eye. 

1,  Anterior  chamber  containing  aqueous  humour; 

2,  Posterior  chamber  ;  3  3,  Canal  of  Petit  ;  4. 
Vitreous  humour ;  a.  Sclerotic  coat  ;  b.  Choroid 
coat ;  c,  Eetina ;  d.  Optic  nerve ;  e  e,  Ciliary  zone  ; 
e'  e',  Ciliary  atuscle  ;  /,  Junction  of  cornea  with 
sclerotic  ;  g,  Ifls  ;  g'.  Pupil;  h,  Crystalline  lens. 


TUNICS    OF    THE    EYEBALL. 

These  are  three  in  number — 1.  The  sclerotic  and  cornea  ; 
2.   The  choroid  and  iris;   3.  The  retina. 

The  sclerotic  coat  and  cornea  form  the  external  tunic,  and  it 
is  to  them  that  the  eyeball  owes  its  peculiar  shape.  About 
four-fifths  of  the  globe  are  invested  by  the  sclerotic,  the 
remaining  fifth  by  the  cornea. 

The  Sclerotic  coat  is  a  dense  white  fibrous  membra.ne,  which 
extends  from  the  insertion  of  the  optic  nerve,  with  the  sheath  of 
which  it  is  continuous,  to  the  cornea.      Its  external  surface  is   in 


TUNICS    OF    THE    EYEBALL. 


533 


Fig.  206. 

Globe  of  the  eye— Antero-lateral 
view,  a,  Sclerotic  ;  6,  Optic  nerve  ; 
c,  c,  Cornea  ;  d,  d,  Eliptic  opening  in 
the  cornea. 


connection  with  the  cellular  and  adipose  tissue,  and  with  the 
muscles  of  the  eyeball,  the  tendons  of  the  four  recti  expanding 
■over  it  and  forming  a  thin  tendinous 
layer,  the  tunica  alhuginea,  which  is 
pa.rtly  covered  by  the  conjunctiva,  and 
forms  the  "white  of  the    eye."     Its 
internal  surface  is  in  contact  with  the 
choroid  coat,  from  which  it  receives  a 
stain,  and  to  which  it  is  united   by 
very  delicate  cellular  tissue,   and  by 
minute  nerve  filaments  and  vascular 
ramifications.      Its  anterior  opening  is 
elliptical,  and  presents  a  bevelled  edge, 
which  receives  the  cornea  in  a  manner 
similar  to  that  in  which  a  watch-glass 
is  received  by  the  groove  in  its  case. 
Posteriorly  it  is  pierced  for  the  passage 
of  the  optic  and  ciliary  nerves,    and 
ciliary  arteries,   the  optic  nerve  fila- 
ments passing  through  numerous  minute  openings  in  the  portion 
called  the  lamina  crihrosa,  the  larger  opening  in  the  centre,  the 
forus  opticus,  being  for  the  passage 
of  the  arteria  centralis  retinas. 

The  Cornea  is  transparent,  ellip- 
tical in  shape,  and  fitted  into  the 
bevelled  edge  of  the  sclerotic,  to 
which  it  is  firmly  adherent.  Its 
anterior  surface  is  convex,  and 
covered  by  a  continuation  of  the 
conjunctiva,  while  its  inner  surface 
is  concave,  and  covered  by  the 
lining  membrane  of  the  anterior 
chamber  of  the  eyeball. 

The  cornea  is  composed  of  two 
layers  ;  the  cornia  propria  and  the 
cornea  elastica.  The  former  con- 
sists of  several  thin  lamellae,  held 
together  by  extremely  fine  areolar 
tissue  ;  the  latter  is  a  fine,  elastic, 
and  exquisitely  transparent  membrane,  closely  applied  to  the  inner 
surface  of  the  propria.      It  retains  its  transparency  long  after  the 


Fio.  207. 

Globe  of  the  eye— part  of  the  sclerotic 

reflected  away,    a,  Sclerotic  ;   b,  Mem- 

brana   f  usca ;    c.    Choroid,    with  ciliary 

nerves. 


534  -ffiSTHESIOLOGY. 

other  has  become  opaque,  and  from  its  great  elasticity,  its  use 
is  supposed  to  be  that  of  preserving  the  correct  curvature  of  the 
flaccid  cornea  propria. 

The  proper  cornea  is  continuous  with  the  sclerotic  coat,  and 
the  elastic  one  with  the  ciliary  muscle. 

The  Second  Tunic  of  the  eyeball  is  formed  by  the  choroid 
coat  and  iris. 

The  Choroid  coat  is  a  thin  vascular  membrane,  of  a  brownish 
or  black  colour.  Externally  it  is  connected  to  the  sclerotic  by 
means  of  a  fine  areolar  tissue,  the  membrana  fusca,  minute  blood- 
vessels, and  nerves;  internally  it  is  in  simple  contact  with  the 
retina ;  posteriorly  it  is  pierced  for  the  passage,  of  the  optic  nerve  ; 
and  anteriorly,  at  the  junction  of  the  sclerotic  and  cornea,  it  is 
connected  with  a  white  circular  ring,  the  ciliary  muscle,  which  is 
continuous  with  the  circumference  of  the  iris. 

The  choroid  membrane  is  composed  of  three  layers  ;  external, 

middle,  and  internal.      The  external  layer  consists  principally  of 

veins,  vence  vorticosoe,  arranged  in  peculiar  curves,  all  of  which 

converge  to  four  or  five  trunks,  which  pierce  the  middle  of  the 

sclerotic  ;  the  largef  branches  of  the  short  ciliary  arteries  mingle 

with  the  veins,  and  the  numerous  pigment 

I  cells,  to  which  the  outer  colour  of  the  choroid 

jBBl^I^^B^  is  due,  are  interspersed  among  the  vessels. 

^BP^^aBst         This  layer    is    connected  with   the   ciliary 

^flnM^^S^^      muscle.     The  middle  layer  is  formed  by 

I^W^bPE9      the  ciliary  arteries,  which  ramify  into  a  fine 

capillary    plexus,  formerly  known    as    the 

tunica  Ruyschiana,  which  is  reflected  in- 

FiG  208  wards,  and  is  continuous  with  the  ciliary 

Pigment  cells,    a.    The     proccsses.     The  internal  or    pigmentary 

Pigment  granules  conceal-     i^y^^  ig  composod  of  lam  in  SB  of  hexagOnal 

ing    the    nucleus,     b,    The  ^  .    .  •,  ,      i  •  i 

nndcus  visible.  cells,   contamiug  black    pigment  granules, 

and  arranged  in  a  tesselated  form.  On 
the  posterior  wall  the  black  pigment  is  absent,  causing  a  peculiar 
bluish  lustre,  which,  owing  to  its  brilliancy,  has  received  the 
name  of  the  tapetum  lucidum. 

The  ciliary  Tnuscle  is  a  white  ring  of  fibres,  which  forms  the 
bond  of  union  between  the  external  and  middle  tunics  of  the  eye, 
and  serves  to  connect  the  cornea  and  sclerotic  with  the  external 
layer  of  the  choroid  and  with  the  iris.  A  minute  vascular  canal,  the 
ciliary  canal,  exists  between  this  ligament  and  the  sclerotic  coat. 


V9 


TUNICS    OF    THE    EYEBALL.  535 

The  Ciliary  processes,  from  sixty  to  eighty  in  number,  and 
arranged  in  a  circle,  are  formed  by  the  plating  or  folding  inwards 
of  the  middle  and  inner  layers  of  the  choroid  ;  their  circumfer- 
ence is  attached  to  the  ciliary  muscle,  and  their  central  border  is 
received  between  corresponding  foldings  of  the  suspensory  liga- 
ment of  the  crystalline  lens,  or  zonula  of  Zinn.  The  anterior 
face  of  these  processes  is  turned  towards  the  back  of  the  iris,  and 
the  posterior  face  closely  connected  with  the  zonula  of  Zinn, 
through  which  connection  a  communication  is  established  between 
the  inner  and  choroid  tunics  of  the  eyeball.  Externally,  they  are 
covered  with  a  thick  layer  of  pigmentary  cells. 

The  Iris  is  a  thin  diaphragm  oi  curtain;  suspended  imme- 
diately in  front  of  the  crystallii  3  lens,  its  periphery  being 
connected  with  the  choroid  coat  and  ciliary  muscle,  and  its 
centre  pierced  by  an  elliptical  open- 
ing, the  pupil.  It  is  variously 
coloured,  but  in  the  horse  is  brown, 
with  more  or  less  of  a  yellow  tinge ; 
sometimes,  however,  it  is  almost 
white  or  grey,  when  the  animal  is 
said  to  be  "  wall-eyed."  Its  anterior 
surface  is  slightly  convex,  and  its 
posterior    surface    covered    with   a 

deep     purple     pigment,     called     the         i^s  and  anterior  part  of  choroid  coat- 
UVea,       from       its       resemblance      in      internal  view,     a,  Pupil ;  6,  ClUary  pro- 
,  ,  .  cesses. 

colour  to  a  ripe  grape. 

Two  sets  of  fibres  enter  into  the  formation  of  the  iris,  one v of 
which,  converging  from  the  circumference  towards  the  centre,  has 
the  power  of  dilating  the  pupil ;  the  other,  surrounding  the  mar- 
gin of  the  pupil  on  its  posterior  surface,  and  blending  with  the 
radiating  fibres,  has  the  pov/er  of  contracting  it. 

In  the  foetus,  the  pupil  is  closed  by  a  delicate  transparent 
vascular  membrane,  the  membrfina  pupillaris,  which  begins  to 
be  absorbed  a  short  time  before  birth,  the  absorption  com- 
mencing at  the  circumference.  At  the  period  of  birth  it  is 
almost  entirely  removed. 

The  small  bodies  situated  on  the  upper  pupillary  margin  of 
the  iris,  three  or  four  in  number,  are  the  corpora  nigra,  their 
ase  appearing  to  be  that  of  concentrating  the  rays  of  light,  and 
preventing  their  too  direct  passage  through  the  pupil. 

Third  Tunic. — The  last  tunic  of  the  eye  is  the  Retina,  which 


536 


.(ESTHESIOLOGY. 


is  prolonged  forwards  to  the  ciliary  processes.  The  retina  is  the 
terminal  expansion  of  the  optic  nerve,  over  the  internal  face  of 
the  choroid  coat,  from  which  it  is  easily  separated.  It  is  com- 
monly described  as  consisting  of  nine  layers,  arranged  as  follows 
from  within  outwards  : — 1.  Internal  limiting  layer;  2,  Optic 
nerve  fibres ;  3.  Ganglionic  cells ;  4.  Internal  molecular  layer  ; 
5.  Internal  granular  layer ;  6.  External  molecular  layer  ; 
7.  External  granular  layer ;  8.  External  limiting  membrane  ; 
9.  Basilary  layer,  or  rods  and  cones.  The  vascular  portion 
consists  of  the  ramifications  of  the  arteria  centralis  retinae  and 
its  satellite  vein,  their  branches  being  continued  into  the  zonula 
of  Zinn. 

The  Ciliary  zone,  or  Zonula  of  Zinn,  is  a  thin  vascular 
layer,  which  connects  the  anterior  margin  of  the  retina  "with 
the  anterior  surface  of  the  lens,  and  presents  a  number  of  folds 
which  are  received  between  the  corre- 
sponding folds  of  the  ciliary  processes. 
The  under  surface  of  this  zone  is 
in  contact  with  the  hyaloid  mem- 
brane, and  is  separated  from  the 
circumference  of  the  lens  by  the 
small  circular  canal  termed  the  canal 
of  Petit 


Fig.  210. 
Olobe  of  the  eye  seen  from  before 
— the  cornea  and  aqueous  humonr 
removed.  1,  Sclerotic  ;  2,  Anterior 
part  of  choroid ;  a  a,  Ciliarj-  muscle  ; 
b  b,  Iris;  c,  Pupil;  d  d,  Corpora 
nigra. 


HUMOURS    OF    THE    EYE. 


These,  the  refracting  media,  are 
three  in  number;  the  aqueous  and 
vitreous  humours,  and  the  crystalline 
lens. 
The  aqiieous  humour  consists  chiefly  of  water,  possessing  an 
alkaline  reaction,  and  completely  fills  the  anterior  and  posterior 
chambers  of  the  eye.  The  anterior  chamber  is  the  space  inter- 
vening between  the  internal  face  of  the  cornea  and  the  iris,  pupil, 
and  ciliary  muscle.  The  posterior  chamber,  ignored  by  some 
authorities,  is  the  very  narrow  space  bounded  in  front  by  the  iris, 
and  behind  by  the  capsule  of  the  lens  and  zonula  ciliaris.  Both 
chambers  are  lined  by  a  thin  membrane,  which  secretes  the 
aqueous  humour. 

The  vitreous  hv/mour  occupies  about  four-fifths  of  the  whole 
interior  of  the  globe.     It  is  a  highly  albuminous  and  perfectly 


MUSCLES    OF    THE    EYE.  537 

transparent  substance,  of  the  consistence  of  jelly,  enclosed  in  a 
delicate  membrane,  the  hyaloid,  from  the  inner  surface  of  which 
numerous  lamellae  are  sent  inwards,  to  form  the  compartments  in 
which  the  fluid  portion  is  contained. 

The  crystalline  humour,  or  lens,  is  situated  immediately  behind 
the  pupil,  in  front  of  the  vitreous  humour,  and  is  surrounded  by 
the  ciliary  processes,  which  slightly  overlap  its  margin.  It  is 
biconvex,  the  convexity  of  the  posterior  face  being  the  greater, 
and  is  enveloped  by  a  transparent  elastic  membrane,  the  capsule 
of  the  lens,  which  is  connected  with  its  surface  by  a  layer  of  trans- 
parent cells.  After  death,  these  cells  absorb  fluid  from  the  eye, 
and  break  down  into  the  liquor  Ilorgagiii.  The  'lens  is  con- 
structed of  concentric  layers  or  laminae,  of  which  the  external  are 
soft,  and  the  internal  firmer  It  is  supported  in  its  place  by  the 
■ciliary  zone. 

MUSCLES    OF    THE    EYE. 

The  intrinsic  or  motor  muscles  of  the  globe  of  the  eye  are 
seven,  five  of  which  are  straight  muscles — viz.,  the  posterior 
or  retractor,  the  superior  or  levator,  the  inferior  or  depressor,  the 
external  or  abductor,  and  the  internal  or  adductor;  the  remain- 
ing two  are  the  oblique  muscles,  distinguished  as  superior,  and 
inferior.'"' 

The  Rectus  oculi  posterior,  or  Retractor  oculi,  com- 
pletely envelopes  and  forms  a  sheath  round  the  extra-cranial 
portion  of  the  optic  nerve.  It  originates  from  the  edge  of  the 
optic  foramen,  and  is  inserted  to  the  posterior  part  of  the  external 
face  of  the  sclerotic,  its  action  being  to  retract  the  eye  within 
the  orbit. 

The  remaining  four  Recti  muscles  have  their  origin  round 
the  margin  of  the  optic  foramen,  within  the  orbit,  and  become 
inserted  by  a  broad  expansion,  which  forms  the  tunica  albuginea, 
on  the  anterior  portion  of  the  sclerotic  coat.  These  four  muscles 
form  a  fleshy  sheath  round  the  eyeball,  similar  to  that  which  the 
retractor  forms  round  the  optic  nerve.  They  are  all  flat  and 
ovoid  in  form,  the  narrowest  part  being  at  their  origin.  Acting 
together,  they  retract  the  eyeball ;  singly,  the  superior  rectus 
turns  the  eye  upwards  ;  the  inferior  turns  it  downwards ;  the 
internal  turns  it  inwards  ;   and  the  external  turns  it  outwards. 

*  We  may  here  call  attention  to  the  very  small  muscle,  desciibed  by 
Strange  ways  as  a  supernumerary  oblique  muscle — vide  Appendix  II. 


538  ^STHESIOLOGY. 

The  Superior  Oblique  muscle  is  situated  at  the  side  of  the 
internal  and  superior  recti.  It  arises  from  near  the  optic 
foramen,  and  is  directed  forwards  against  the  internal  wall  of 
the  cavity,  passing  through  a  cartilaginous  loop  at  the  base  of 
the  orbital  process  of  the  frontal  bone,  near  the  inner  canthus, 
whence  it  is  directed  backwai:ds,  and  under  the  terminal  extremity 
of  the  superior  rectus,  to  become  inserted  to  the  sclerotic,  between 
the  superior  and  external  recti.  The  action  of  this  muscle  is  to 
elevate  and  rotate  the  eyeball. 

The  Inferior  or  Lesser  Oblique  arises  from  the  lachrymal 
fossa,  is  carried  obliquely  outwards,  and  is  inserted  to  the  sclerotic 
between  the  external  and  inferior  recti  muscles.  Its  action  being 
to  depress  and  turn  the  eye  inwards,  is  antagonistic  to  that  of 
the  superior  oblique  muscle. 

Professor  Turner  has  described  a  non-striated  mass  of  muscular 
fibres  connected  with  the  periosteum  of  the  orbit.  (See  Appen- 
dix III.) 

appendages  of  the  eye. 

The  accessory  parts  or  appendages  of  the  eye,  are  the  eyebrows, 
eyelids,  membrana  nictitans,  conjunctiva,  caruncula  lachry- 
malis,  lachrymal  apparatus,  and  ocular  sheath. 

The  Eyebrows,  very  rudimentary  in  the  horse,  are  the  emin- 
ences formed  by  the  orbital  processes  of  the  frontal  bone.  They 
are  furnished  with  a  few  long  hairs,  and  serve  to  interrupt  the 
too  vivid  rays  of  light,  and  prevent  foreign  bodies  from  descending 
into  the  eyes. 

The  Eyelids  are  the  two  moveable  curtains,  superior  and 
inferior,  which  protect  the  eye.  Both  are  capable  of  expansion 
and  contraction,  though  the  superior  is  the  larger  and  more 
movable  of  the  two.  When  drawn  apart,  they  form  an  elliptical 
opening,  the  angles  of  which  are  termed  the  canthi.  The  outer 
canthus,  or  temporal  angle,  is  acute  ;  the  inner  canthus,  or  nasal 
angle,  is  more  obtuse  or  rounded,  and  it  contains  the  caruncula 
lachrymalis.  The  external  surface  of  the  eyelids  is  covered  with 
fine  short  hairs  ;  the  internal  surface  is  smooth,  lined  by  the 
conjunctiva,  a  continuation  of  the  skin  modified,  and  is  in  contact 
with  the  globe  of  the  eye.  Their  free  borders  are  thick,  and  on 
their  margins  are  rows  of  long  hairs,  the  eyelashes,  or  cilia,. 
which  serve  to  prevent  the  intrusion  of  foreign  bodies.  The 
ciliary  borders  of  the  lids  also  present  a  series  of  minute  openings^ 
■which  are  the  ducts  of  the  Meibomian  glands. 


APPENDAGES    OF    THE    EYE.  539 

Entering  into  the  structure  of  the  eyelids,  there  are,  therefore, 
«kin,  muscles,  fibrous  tissue,  tarsal  cartilage,  Meibomian  glands, 
and  conjunctiva.  The  skin  covering  the  eyelids  is  very  fine,  and 
adheres  intimately  to  the  levator  palpebrse  and  orbicularis  palpe- 
brarum muscles.  The  fibrous  tissue,  thickest  in  the  inferior  eye- 
lid, is  firmly  attached  by  its  adherent  border  to  the  periosteum 
of  the  orbit,  and  the  bone  under  the  eyebrow,  and  by  its  free 
border  to  the  tarsal  cartilage,  hence  it  is  sometimes  termed  the 
tarsal  ligament.  The  tarsal  cartilages  are  the  two  cartilaginous 
plates  which  form  the  solid  framework  of  the  free  border  of  the 
eyelids.  They  are  elongated,  narrowest  at  their  extremities,  and 
thin  on  their  attached  borders,  which  are  continuous  with  the 
fibrous  membrane.  These  cartilages  afford  a  firm  and  very  pliant 
support  to  the  eyelids,  and  present  on  the  side  next  the  globe  of 
the  eye  a  series  of  vertical  furrows,  which  lodge  the  ciliary 
follicles.  The  tarsal  cartilage  of  the  superior  lid  is  longer  and 
thicker  than  that  of  the  inferior. 

The  Ciliary  Follicles,  or  Meibomian  Glands,  are  situated 
between  the  tarsal  cartilages  and  the  conjunctiva  Each  gland 
consists  of  a  single  tube,  into  which  a  cluster  of  follicles  opens, 
and  the  whole  row  of  glands  along  the  edge  of  the  cartilage  bears 
a  strong  resemblance  to  a  string  of  beads.  These  glands  secrete: 
a  sebaceous  fluid,  which  prevents  the  eyelids  adhering  together.- 
during  sleep. 

The  Conjunctiva,  the  mucous  membrane  of  the  eye,  is  very 
thin  and  very  vascular,  its  vascularity  being  greatest  on  the  inner 
surface  of  the  lids,  and  least  on  the  cornea,,  where  in  health  no 
vessels  are  traceable.  It  lines  the  entire  inner  surface  of  the  eye- 
lids, being  continuous  with  the  skin  on  their  edges,  covers  the 
anterior  part  of  the  membrana  nictitans,  and  passes  down  the 
nasal  duct.  It  is  reflected  over  the  whole  of  the  anterior  portiom 
of  the  globe ;  adhering  very  loosely  to  the  sclerotic  and  aponeu- 
rotic expansion  of  the  recti  muscles,  and  very  firmly  to  the  cornea, 
where  it  is  extremely  delicate  and  transparent. 

The  Membrana  nictitans,  or  accessory  eyelid,  vulgarly  the 
"  haw  of  the  eye,"  is  situated  near  the  nasal  angle,  between  the 
globe  and  the  side  of  the  orbit.  It  is  composed  of  elastic  fibro- 
cartilage,  and  is  irregular  in  form,  being  thick  and  somewhat 
prismatic  at  its  base,  and  thin  anteriorly,  where  it  is  covered  by 
a  fold  of  conjunctiva.  Posteriorly,  it  is  continuous  with  the  pad 
of  fat  which   is  insinuated   between  all   the  muscles  of  the  eye. 


540  ^STHESIOLOGY. 

Its  external  surface  is  convex,  and  its  internal  concave.  Wheri 
the  eye  is  in  its  natural  position,  only  the  margin  of  the  mem- 
brana  nictitans,  covered  by  conjunctiva,  is  perceptible,  the  rest 
being  buried  in  the  ocular  sheath  ;  but  when,  by  the  contraction 
of  the  straight  muscles,  the  globe  presses  upon  the  pad  of  fat,  the 
membrane  is  forced  out,  and  covers  more  or  less  of  the  trans- 
parent cornea.  This  movement,  which  is  instantaneous,  is  for 
the  purpose  of  removing  any  offending  agent  from  the  surface  of 
the  eye.  In  some  diseases,  as  tetanus,  this  membrane  is  forced 
outwards,  and  remains  so. 

A  very  small  reddish-yellow  gland,  the  gland  of  Harder,  ia 
found  near  the  middle  of  the  outer  surface  of  the  membrana  ; 
it  is  covered  by  fat  and  fibrous  tissue,  and  it  secretes  an  unctuous, 
lubricating  fluid,  which  is  poured  on  the  internal  surface  of  the 
cartilage,  by  several  small  openings.  All  authorities  do  not 
describe  this  gland. 

The  Caeuncula  lachetmalis  is  the  smdl  round  body,  of  a 
reddish  colour,  seen  in  the  inner  canthus.  It  consists  of  a  num- 
ber of  follicles,  and  the  bulbs  of  soft,  fine  hairs.  Its  use  is  to 
direct  the  tears  towards  the  puncta  lachrymalia. 

LACHRYMAL  APPARATUS. 

The  lachrymal  apparatus  consists  of  the  lachrymal  gland, 
lachrymal  canals,  lachrymal  sac,  and  nasal  duct. 

The  Lachrymal  gland,  situated  between  the  orbital  process 
and  the  superior  straight  muscle,  is  convex  superiorly,  concave 
inferiorly,  thickest  and  broadest  anteriorly,  and  thinnest  and 
narrowest  posteriorly.  It  belongs  to  the  class  of  conglomerate 
glands,  is  of  a  pale  yellow  colour,  and  consists  of  numerous 
lobules,  composed  of  sacculi  and  tubes  held  together  by  cellular 
tissue.  The  secretion,  which  constitutes  the  tears,  destined  to 
lubricate  the  anterior  surface  of  the  eye,  escapes  through  numerous 
straight  ducts,  hygrophthalmic  canals,  which  open  on  the  surface 
of  the  conjunctiva  underneath  the  upper  lid,  and  towards  the 
outer  canthus  5  it  iu  carried  between  the  lids  and  the  globe 
towards  the  inner  canthus,  and  enters  two  small  openings,  the 
■puncta  lachrymalia,  one  on  each  side  of  the  caruncula  lachry- 
malis.  These  puncta  lachrymalia  are  the  openings  of  the  minute 
lachrymal  canals,  which  are  formed  in  the  substance  of  the  eye- 
lids, and  are  lined  by  a  continuation  of  the  conjunctiva ;  they 


SKIN    AND    ITS    APPENDAGES.  541 

enter  the  lachrymal  sac,  the  superior,  being  the  longer,  a  littie 
behind  the  inferior. 

The  Lachrymal  sac  is  a  small  reservoir  lodged  in  a  fossa  in 
the  lachrymal  bone,  and  is  the  origin  of  the  lachrymal  duct. 

The  Lachrymal  or  Nasal  duct  (ductus  ad  nasum)  is  a  long 
membranous  canal,  which  begins  at  the  sac,  passes  through  a 
conduit  in  the  bone,  and  terminates  on  the  internal  face  of  the 
nasal  opening,  on  the  skin,  near  to  and  a  little  above  the  inferior 
commissure  of  the  ala  ;  it  sometimes  terminates  in  two  openings. 
Tt  is  lined  by  a  continuation  of  the  conjunctiva,  which  also  lines 
the  lachrymal  canals  and  sac  In  some  animals  it  is  partly  lined 
by  an  inflexion  of  the  mucous  membrane  of  the  nostril. 

The  Ocular  sheath  is  a  dense  fibrous  membrane  lining  the 
orbit  and  enclosing  its  contents.  It  is  strongest  supero-externally, 
where  the  cavity  is  deficient  in  osseous  boundary.  It  has  been 
said  that  this  membrane  is  continuous  with  the  dura  mater,  to 
which  it  bears  resemblance  in  structure. 

The  senses  of  Taste  and  Smell  rest  respectively  in  the  tongue 
and  nasal  chambers,  which  have  previously  been  considered 

Skin  and  its  Appendages. 

The  skin  and  its  appendages  constitute  the  exoskeleton  or 
external  casing  of  the  body.  The  skin  itself  consists  of  two 
parts,  the  dermis,  cutis  vera,  or  corium,  which  forms  the  deep 
layer,  and  the  epidermis  or  cuticle,  superficially  placed.  Its 
chief  appendages  are  glands,  and  the  epithelial  modifications, 
hair,  horn,  and  hoof. 

The  Epidermis,  cuticle,  or  scarf  skin,  is  an  epithelial  structure, 
forming  a  protective  covering  to  the  corium.  It  varies  in  thick- 
ness, is  quite  insensitive  and  non-vascular,  and  consists  of  agglu- 
tinated cells  which  are  formed  on  the  surface  of  the  true  skin  ; 
they  contain  nuclei,  vary  in  form,  the  deep  layers  being  columnar, 
those  above  rounded,  those  on  the  surface  flat,  being  finally  cast 
off  as  dry,  desquamating  scales.  They  also  change  in  physical  and 
chemical  constitution,  the  deep  ones  being  soft  and  opaque,  the 
superficial  dry,  horny,  and  soluble  in  acetic  acid.  Their  fluid 
portion  when  pressed  out  serves  to  cement  them  together.  The 
epidermis  is  divided  into  a  firm  and  transparent  superficial  and  a 
deep  soft  layer.      The  latter  is  the  rete  mucosum,  in  whose  cells 


542  ^STHESIOLOGY. 

the  pigment  exists  which,  gives  colour  to  the  skin.  The  deep 
surface  of  the  epidermis  is-  accurately  moulded  on  the  papillary 
layer  of  the  true  skin,  and,  when,  removed  by  maceration, 
presents  depressions,  which  correspond  to  the  elevations  on  the 
dermis  ;  from  the  cuticle,  tubular  prolongations  pass  into  the 
•sebaceous  and  sudoriferous  glands.  The  outer  surface  is  marked 
by  a  network  of  furrows,  the  deep  ones  forming  lozenge-shaped 
spaces. 

The  Dermis,  or  true  skin,  is  vascular  and  higlily  sensitive, 
being  the  seat  of  touch.  It  is  attached  to  the  underlying  parts 
by  a  layer  of  areolar  tissue,  which  iisually  contains  fat,  hence 
called  the  pannicidus  adiposus.  The  dermis  consists  of  fibro- 
areolar  tissue  and  vessels  of  supply ;  it  is  divided  into  two  layers, 
the  deep  or  true  corium,  and  the  upper  or  papillary.  The 
deep  corium  consists  of  strong  interlacing  fibrous  bands,  chiefly 
white  ;  its  meshes  are  larger,  and  more  open  towards  the  attached 
surface,  giving  lodgment  to  the  sweat-glands  and  fat.  The 
papillary  or  superficial  layer  is  formed  of  a  series  of  small  conical 
eminences  or  papillae,  which  are  highly  sensitive,  and  consist  of  a 
homogeneous  transparent  tissue.  The  blood-vessels  form  dense 
capillary  plexuses  in. the  corium,  terminating  by  loops  in  the 
papillae.  The  papillary  nerves  run  in  an  undulating  manner, 
aisu^lly  terminating  in  loops. 

GLANDS    OF    THE    SKIJ^. 

These  are  the  sebaceous  and  sudoriferous. 

The  Sebaceous  glands,  lodged  in  the  corium,  are  most 
abundant  in  parts  exposed  to  friction.  They  generally  open  into 
the  hair  follicles,  and  occasionally  on  the  surface  oi  the  skin. 
Each  gland  consists  of  a  small  duct,  which  terminates  in  a 
lobulated  recess.  These  lobules  vary,  and  are,  as  is  the  duct, 
lined  with  epithelium.  They  are  filled  with  sebaceous  matter, 
which,,  as  it  is  secreted,  is  discharged  into  the  hair  sacs. 

The  Sudoriferous  or  sweat  glands  are  situated  in  the  sub- 
cutaneous areolar  tissue,  surrounded  by  a  quantity  of  fat.  They 
are  small,  round  reddish  bodies,  each  of  which  consists  of  one  or 
more  fine  tubes  coiled  into  a  ball,  the  free  end  of  the  tube  being 
continued  up  through  the  true  skin  and  cuticle,  and  opening  on 
the  surface  by  a  funnel-shaped  orifice.  Sometimes  there  are  two 
apparent  ducts,  which  unite  at  a  short  distance  from  the  gland. 


HATTl.  543 

The  ducts  are  slightly  curved  as  they  pass  through  the  corium. 
Where  the  scarf  skin  is  thick,  they  assume  a  spiral  appearance ; 
where  it  is  thin,  they  open  directly  out.  They  consist  of  two 
coats;  an  outer,  continuous  with  the  corium,  and  an  inner 
epithelial  one,  which  is  continued  to  the  surface.  Each  sweat- 
gland  is  supplied  with  a  cluster  of  capillary  blood-vessels.  Their 
size  varies,  being  very  large  where  perspiration  is  excessive.  The 
contents  of  the  smaller  glands  are  quite  fluid,  those  of  the  larger 
contain  fine  granules. 

The  skin  of  the  horse  is  characterised  by  its  great  sensitiveness, 
which  is  still  further  promoted  by  the  operation  of  gi-oomiug,  an-d 
artificial  protection  ;  and  also  by  the  development  and  activity  of 
the  sudoriferous  apparatus ;  few  animals,  if  any,  perspire  so  freely 
as  the  horse.  The  large  quantity  of  pigment  found  in  the  skin 
is  believed  to  serve  as  a  protection  against  the  heat  of  the  suil 
An  epithelial  excrescence  appears  on  the  distal  part  of  the  fore- 
arm internally,  an,d  on  the  proximal  portion  of  the  metatarsus 
also  internally  ;  these  objects,  ergots  or  chesnnts,  the  "chataignes" 
of  French  authors,  according  to  Chauveau,  "  represent  the  vestige 
of  the  thumb." 

HAIR. 

Hair  is  an  appendage  of  the  skin,  and  in  most  mammals  forms 
its  external  covering.  It  is  a  special  modification  of  epidermis, 
having  in  its  bulk  the  same  essential  structure.  A  hair  consists 
of  a  root,  a  shaft,  and  a  point.  The  root  has  a  bulbous  enlarge- 
ment at  its  extremity,  is  lighter  and  softer  than  the  shaft,  and  is 
lodged  in  a  recess  or  hair  follicle,  which  may  either  be  in  the 
corium  or  subcutaneous  areolar  tissue. 

The  follicle  is  dilated  at  the  bottom,  to  correspond  to  the 
root  bulb,  and  the  ducts  of  one  or  more  sebaceous  glands  open 
into  it.  It  consists  of  two  coats ;  an  outer  or  dermic,  an  inner 
or  ctitlcular.  The  outer  composed  of  areolar  tissue,  is  highly 
vascular,  continuous  with  the  corium,  and  possesses  numerous 
minute  nerve  fibrils ;  the  inner,  continuous  with  the  cuticle,  is 
attached  at  the  base  of  the  follicle  to  the  root  of  the  hair.  The 
lining  adheres  to  a  hair  when  plucked  out,  forming  the  root 
sheath.  At  the  bottom  of  each  follicle  is  a  conical  vascular 
papilla,  similar  in  every  respect  to  those  on  the  surface  of  the 
skin.  This  papilla  fits  into  a  corresponding  depression  in  the 
root  of  the  hair. 


5  4)  4  ^STHESIOLOGT. 

The  hair  shaft  consists  of  a  centre  or  medulla,  a  surrounding 
portion,  and  an  external  coating  or  cortex.  The  medulla  consists 
of  cells  containing  pigmentary  matter,  is  opaque,  and  usually 
deeply  coloured.  \J1  hair  has  not  this  medulla.  The  surround- 
ing portion  occupies  the  bulk  of  the  shaft,  and  is  composed  of 
elongated  cells,  which  form  horny  fusiform  fibres.  The  cortex  is 
merely  a  single  layer  of  thin,  flat,  imbricated  scales,  which  assume 
a  different  appearance  in  the  hair  of  animals  of  different  species. 

About  the  muzzle  of  the  horse  are  a  numberr  of  largely-deve- 
loped and  strong  hairs,  commonly  known  as  the  cat-hairs,  from 
their  resemblance  to  the  whiskers  of  a  cat.  These  are  media  of 
touch,  their  bulbs  receiving  filaments  of  sensory  nerves. 


Foot. 

In  equine  anatomy  the  word  "  foot "  implies  the  hoof,  together 
with  the  bones  and  soft  structures  contained  therein.  Many  of 
these  objects  have  already  been  described,  so  that  our  descrip- 
tion here  will  be  confined  almost  entirely  to  the  hoof  and  the 
internal  structures  with  which  it  comes  into  immediate  contact. 
In  the  broad  sense  we  may  regard  the  foot  as  consisting  of 
three  well-marked  portions, — the  basis  or  skeleton  ;  the  highly- 
sensitive  secreting  portion  ;  and  the  non-sensitive  protective 
portion.  The  two  latter  may  be  regarded  as  modifications  of  the 
skin  ;  the  sensitive  part  corresponding  to  the  dermis  or  true  skin, 
while  its  covering,  the  hoof,  corresponds  to  the  epidermis,  both 
the  latter  structures  being  composed  of  a  modified  form  of  epi- 
thelium, and  each  being  secreted  by  the  sensitive  structures 
within. 

The  study  of  the  foot  of  the  horse  is  of  the  greatest  practical 
importance,  owing  to  the  many  diseases  and  injuries  to  which  it. 
IS  liable.  It  resolves  itself  h-re  into  the  >'onsideration  of  the 
hoof  or  horny  case,  and  the  pa"ts  containeii  within  it. 


HOOF. 

The  hoof  of  the  horse  corresponds  to  the  finger-nail  of  man, 
but  it  is  developed  over  the  sides,  and  plantar  aspect  of  the 
distal  phalanx,  thus  forming  a  protective  horny  case,  enveloping^ 
the  inferior  extremity  of  the  digit.  It  is  applied  in  an  exact 
manner  to,  and  united  most  intimately  with,  the  sensitive  struo- 


WALL.  545 

tures  which  lie  within,  this  union  being  effected  by  reciprocal 
depressions  and  elevations  of  the  two  surfaces,  which  fit  into  or 
receive  each  other.  The  general  form  of  the  hoof  somewhat 
resembles  that  of  the  section  of  a  cylinder  which  has  been  cut 
obliquely  across. 

By  maceration,  the  hoof  is  divisible  into  three  distinct  parts  ; 
the  wall,  the  sole,  and  the  frog,  which  we  will  endeavour  to 
describe  separately. 

WALL. 

The  wall  is  that  part  which  is  visible  when  the  hoof  rests  on 
the  ground,  and  is  generally  divided  into  the  toe,  quarters,  heels, 
bars,  internal  and  external  surfaces,  and  superior  and  inferior 
borders.  The  toe  forms  the  front  of  the  hoof,  and  is  the  deepest 
as  Trell  as  the  thickest  part  of  the  wall,  which  gradually  declines 
in  height  as  it  passes  backwards  to  form  the  quarters ;  these 
occupy  the  space  between  the  toe  and  heels.  The  wall  decreases 
in  thickness  from  before  backwards,  more  markedly  so  at  the 
inner  portion.  It  also  apparently  decreases  in  obliquity ;  but  on 
careful  examination,  it  is  found  that  the  fibres  of  the  quarters 
have  the  same  degree  of  obliquity  as  those  of  the  toe.  At  the 
posterior  part  of  the  foot,  the  wall  takes  on  each  side  a  sudden 
bend,  forming  an  acute  angle,  and  is  continued  inwards  to  the 
centre  of  the  foot,  where  the  two  parts  unite  with  the  sole.  The 
angles  of  inflection  are  called  the  heels,  the  inflections  themselves 
the  bars  ;  these  latter  forming  stays  to  the  quarters.  The  ex- 
ternal surface  of  the  wall  is  convex,  smooth,  and  covered  by  a 
thin  layer,  the  periople,  which  is  continuous  above  with  the 
coronary  frog  band.  The  internal  surface  of  the  wall  presents 
throughout  its  whole  extent  white,  parallel,  perpendicular  plates 
or  processes  of  horn,  the  so-called  keratophyllous  tissue,  which 
extend  from  the  coronary  border  to  the  sole,  and  are  continued 
over  the  inner  surface  of  the  bars.  These  insensitive  or  horny 
lamina  vary  from  500  to  600  in  number,  and  are  separated 
from  each  other  by  deep  fissures,  in  which  are  inserted  the 
sensitive  laminse.  In  the  fresh  subject  the  horny  laminae  are 
soft,  elastic,  and  consist  of  two  layers  of  fibres  ;  one  running 
parallel  with  themselves,  and  others  obliquely  projecting  from 
them.  The  superior  or  coronary  border  of  the  wall  presents 
an  excavation  or  groove,  which  slopes  somewhat  obliquely  down- 
wards  and    inwards,  forming    a    circular    gutter,    the   cutigeral 

2n 


546  iESTHESIOLOGY. 

groove,  in  which  is  lodged  the  coronary  substance  or  hand.  In 
this  srroove  are  numerous  minute  orifices,  in  which  are  inserted 
the  secretory  villi  of  the  coronary  band.  The  infeo'ior  border  is 
that  part  in  contact  with  the  ground,  and  to  which  the  shoe  is 
fitted.  In  an  unshod  animal  it  is  always  in  wear,  and  protrudes 
beyond  the  rest,  more  especially  round  the  outer  quarter,  and  is 
known  as  the  spread.  The  inner  surface  of  the  inferior  border 
is  united  in  a  very  intimate  •  manner  with  the  periphery  of  the 
sole.  The  external  layer  of  horn  in  the  wall  is  distinctively 
known  as  the  crust,  and  is  secreted  by  the  coronary  band  ;  the 
rest  being  secreted  by  the  sensitive  laminae. 

Supposing  the  hoof  to  rest 
on  a  perfectly  level  plane,  the 
line  joining  the  toe  to  the 
middle  of  the  coronary  border 
should  make  with  the  ground 
an  angle  of  about  5  0  degrees 
in  the  fore,  and  perhaps  a  little 
more  in  the  hind  feet.  An 
angle  exceeding  or  falling  short 
Fio.  211.  to  any  extent  of  this,  would 

Detached  hoof— supero-iaterai  view,  a,  Crust,     indicate  defective  Conformation. 

or  outer  layer  of  the  waU  ;  b  Homy  lamina,;  j  ^j^-  particular,  hoWCVCr,  it 
c,  Supenor  border  ;  d,  Cutigeral  groove ;  e,  Inner        _  1  '  ' 

surface  of  sole  ;  /,  Inner  surface  of  frog  ;  /',  Frog-       is    nCCCSSary     tO     make     alloW- 

**''■  ances  for  many  circumstances, 

such  as  the  breed  and  age  of  the  animal,  the  condition  of  the 
foot,  &c,,  which  may  influence  the  angle. 


SOLE. 

The  sole  is  a  thick  plate  of  horn,  which  helps  to  form  the 
inferior  portion  of  the  hoof.  It  is  comprised  between  the  inner 
border  of  the  inferior  part  of  the  wall  and  the  inflections  or  bars, 
a,nd  presents  two  surfaces  and  two  borders.  The  inferior  or 
external  surface  forms  a  vault,  which  is  more  or  less  concave 
in  different  animals.  The  superior  or  internal  surface  is 
unevenly  convex,  and  is  studded  with  a  number  of  small  orifices, 
which  run  obliquely  forwards  ;  into  these  are  inserted  the  vascular 
papillae  of  the  sensitive  sole.  The  external  border  or  circum- 
ference of  the  sole  is  convex,  abuts  upon,  and  is  united  through- 
out its  whole  extent  to  the  internal  part  of  the  inferior  border  of 


FROG  547 

the  wall,  the  union  between  the  two  being  very  intimate,  through 
the  intervention  of  homy  matter.  The  inner  border  represents 
a  deep  cut  or  notch,  in  the  form  of  the  letter  V,  and  is  related 
with  the  bars,  excepting  at  the  narrow  part,  where  it  is  bounded 
by  the  frog.  The  two  angles  uniting  the  outer  and  inner  circum- 
ferences correspond  to  the  heels,  and  are  received  between  the 
wall  and  the  bars  ;  this  part  of  the  sole  covers  the  region  which 
is  most  liable  to  injuries,  especially  to  bruises  or  corns. 


FROG. 


The  frog  is  the  prominent,  somewhat  pyramidal  mass  of 
spongy  horn  lodged  between  the  bars,  and  filling  up  the  trian- 
gular space.  It  has  four  surfaces,  a 
base,  and  an  apes.  The  inferior  or 
external  surface  is  very  irregular,  and 
presentsalongitudinal  triangular  cavity, 
which  varies  in  breadth  and  depth, 
being  broadest  and  deepest  in  well- 
formed'  feet.  This  cavity  is  the  cleft 
of  the  frog,  boundmg  which  are  two 
sloping  projections  or  branches,  which 
unite  at  the  apex  of  the  frog  anteriorly, 
and  diverge  posteriorly  where  they  join 
the  heels.  The  superior  or  internal 
surface  is  also  very  irregular,  but  ex- 
actly the  reverse  of  the  inferior ;  where 
the  one  is  hollow  the  other  has  a  pro- 
jection, and  vice  versa.  It  presents  over 
its  whole  surface  numerous  small  fora- 
mina, into  which  are  inserted  the  vascu- 
lar or  secreting  papillae  of  the  sensitive  frog,  likewise' a  triangular 
excavation,  which  is  divided  posteriorly  into  two  lateral  gutters  by  a 
long  projection  or  elevation,  corresponding  to  the  cleft  on  the  outer 
surface.  This  somewhat  conical  eminence  is  called  the  frog-stay, 
and  it  assists  in  establishing  a  firm  union  between  the  horny  and 
sensitive  frogs.  The  lateral  surfaces  incline  obliquely  from 
above  downwards,  and  from  without  inwards.  In  their  upper 
third  they  are  firmly  united  to  the '  external  surface  of  the  bars, 
and  anteriorly,  to  the  notch  in  the  sole.     Between  the  inferior 


Fio.  212. 
Solar  aspect  of  the  hoof,  a  a,  Bars ; 
6  b,  Solar  border  of  wall ;  c  c,  Line  of 
union  between  wall  and  sole  ;  d,  In- 
ferior aspect  of  sole  ;  d'  d',  Posterior 
branches  of  ^ole ;  e,  Cleft  of  the  frog  ; 
e'  e*,  Lateral  segments  of  frog ;  //, 
Bulbs  of  the  frog;  g.  Point  of  the 
frog. 


548 


^STHESIOLOGY, 


part  of  the  lateral  surfaces  of  the  bars  and  the  frog  are  deep 
triangular  hollows,  called  the  commissures  of  the  frog.  The 
base  or  posterior  extremities  constitute  the  heels  or  bulbs  of  the 
frog ;  these  are  two  round  flexible  and  elastic  eminences,  formed 
by  the  two  extremities,  and  separated  by  the  cleft.  They  cover 
the  two  angles  of  inflection  of  the  walls,  and  are  continued  round 
the  external  part  of  the  superior  surface  of  the  wall  in  the  form  of 
a  band,  which  is  the  coronary  frog  band;  it  is  from  the  inferior 
border  of  this  that  the  thin  covering  of  the  hoof  is  continued. 

». -p.  __    -         The  summit  or  toe  of  the  frog  is  the  anterior 

pointed    portion,   which  is  inserted  into   the 
narrow  part  of  the  notch  in  the  sole. 

HORN    TISSUE. 

The  horn  of  the  hoof  presents  a  fibrous 
appearance,  very  distinct  in  the  wall,  less  so 
in  the  deep-seated  parts  of  the  sole  and  frog, 
and  scarcely  traceable  in  the  superficies  of 
the  sole,  where  there  is  a  continual  disintegra- 
tion or  separation  of  the  horn  in  layers  more 
or  less  extensive.  It  consists  of  minute 
cylindrical  tubes  or  fibres,  which  have  a  direc- 
tion obliquely  downwards  and  forwards,  and 
are  arranged  in  parallel  rows,  forming  layers, 
placed  one  over  .the  other,  and  internally 
lamellae  or  plates,  the  whole  united  together 
by  an  amorphous  or  intertubular  substance. 
Besides  tha  fibres,  plates,  and  intertubular 
substance,  there  i^s  always  more  or  less  pig- 
mentary matter,  which  consists  of  colour-cells 
distributed  amongst  the  concentric  plates  or 
layers  forming  the  walls.  The  horny  fibres  of 
the  sole  hs.ve  the  same  obliquity  as  those 
of  the  walls,  are  secreted  from  the  villi  on 
the  sensitive  sole,  and  finally  united  to  the  wall  round  the 
outer  circumference ;  they  receive  a  few  villi  from  the  inferior 
extrem-ity  of  each  sensitive  lamina. 

The  horn  of  the  frog  differs  considerably  from  that  of  both 
wall  and  sole.  The  tubes  are  much  finer  and  softer,  and  have  a 
flexuous  arrangement       They  are  united  to  those  of  the  walls  a^ 


Fio.  213. 
Transverse  section  of 
the  horn  of  the  wall 
magnified,  o,  Periople  ; 
b,  Horn  tissue ;  c  c,  Homy 
laminae  ;  d  d,  Sensitive 
laminas. 


SOFT    STKUCTURES    OF    THE    FOOT.  549 

the  base,  and  are  secreted  from  the  papillae  on  the  surface  of  the 
sensitive  frog.  The  fibres  of  the  coronary  frog-band  are  very 
fine,  and  are  continued  by  a  delicate  layer  of  fibres,  which  covers 
the  external  surface  cf  the  wall.  Horn  is  tough,  elastic,  flexible, 
and  admirably  adapted  for  protecting  delicate  parts ;  it  is  secreted 
in  the  form  of  cells,  x-  iiich  become  elougated.  The  colour  of  the 
hoof  vanes,  but  it  generally  corresponUo  iii  depth  with  that  of 
the  neighbouring  skin.  It  'is  an  acknowledged  fact,  that  white 
hoofs,  like  white  skin,  are  more  delicate,  porous,  and  prone  to 
disease  than  dark  ones. 

SOFT    STRUCTURES    OF    THE    FOOT 

The  parts  contained  ivithin  the  hoof  are  the  os  pedis,  oa  bavi- 
culare.  the  distal  extremity  of  the  os  coronae,  the  ligaments  by 
which  these  are  connected  together,  the  insertion  of  the  extensor 
pedis  and  flexor  perforans  tendons,  and  the  vessels  and  nerves. 
These  have  been  described  in  their  respective  sections ;  but 
there  are  also  certain  structures  proper  to  the  foot  which  it  is 
necessary  to  describe  here — viz.,  the  lateral  cartilages,  sensi- 
tive frog,  coronary  band,  sensitive  laminae,  and  sensitive  sole. 

The  Lateral  cartilages  are  two  thin  plates  composed  of 
hyaline  cartilage  in  the  middle,  partaking  more  of  the  nature  oi 
fibro-cartilage  towards  the  borders.  They  are  of  an  irregularly 
quadrangular  form,  and  surmount  the  wings  of  the  cofiin  bone , 
•each  presents  two  surfaces  and  four  borders.  The  external 
eurface  is  convex,  the  internal  one  concave,  presenting  numerous 
vascular  grooves,  and  is  continuous  postero-interiorly  with  the 
sensitive  frog.  The  superior  border  is  thin,  generally  convex, 
and  pierced  by  several  foramina  for  vessels  to  pass  to  the  frog; 
the  inferior  border  is  attached  to  the  wing  of  the  os  pedis 
posteriorly,  it  is  inflected  inwards,  and  is  continuous  with  the 
inferior  surface  of  the  sensitive  frog ;  the  posterior  border  is 
slightly  convex,  and  has  a  direction  obliquely  downwards  and 
backwards,  joining  the  superior  and  inferior  borders,  being 
separated  from  the  former  by  an  obtuse  angle ;  the  anterior 
border,  also  directed  obliquely  downwards  and  backwards,  be- 
comes intimately  blended  with  tli^  anterior  lateral  ligament  of 
the  coffin  joint.  The  anterior  borders  of  the  two  lateral  cartilages 
are  united  by  fibrous  expansions  from  the  extensor  tendon  and 
the  above-mentioned  lateral  ligament 


550 


-ESTHESIOLOGY. 


SENSITIVE   STRUCTURES. 

Attached  to  the  inner  surface  of  the  hoof  is  the  sensitive 
portion  of  the  foot,  which  may,  like  the  hoof  itself,  be  divided 
into  the  regions  of  the  wall,  the  sole,  the  frog,  and  the  coronary- 
band.  The  extremity  of  the  digit  has  been  regarded  not  inaptly, 
as  being  enveloped  in  a  sensitive  sheath,  which  extends  upwards 
beyond  the  level  of  the  coffin  joint,  and  becomes  continuous  with 
the  skin.  This  sheath  has  been  called  the  keratogenous  mem- 
brane, since  on  its  outer  surface  it  is  endowed  with  the  function 
of  secreting  horn  tissue,  for  the  renewal  of  various  parts  of  the 
hoof  The  part  of  this  membrane  which  forms  the  ^  coronary 
band  is  villous  or  papillated  ;  that  forming  the  sensitive  wall  is 
laminated,  constituting  what  has  been 
termed  the  podophyllous  tissue  ;  finally, 
that  forming  the  sensitive  sole  and  frog 
is  finely  villous,  and  may  be  called  the 
velvety  tissue. 

The  Sensitive  frog  occupies  the  pos- 
terior and  central  parts  of  the  foot,  filling 
up  the  irregular  space  between  the  lateral 
cartilages,  flexor  tendon,  and  os  pedis. 
Bounded  laterally  by  the  cartilages, 
superiorly  by  the  perforans  tendon  and 
common  integument,  infero- externally 
by  the  horny  frog,  it  is  continuous  with 
the  sensitive  bars  and  sole,  and  the 
coronary  ligament.  Like  the  homy 
frog,  it  presents  two  surfaces,  two  lateral  borders,  a  base, 
and  an  apex.  The  supero-anterior  surface  is  related  with  the 
strengthening  sheath  of  the  flexor  tendon,  the  ligament  of  the 
navicular  joint,  and  the  alse  of  the  os  pedis  ;  the  infero-posterior 
surface  is  covered  by  villi,  from  which  the  homy  frog  is  secreted, 
and  in  its  centre  is  a  deep  cavity  for  the  insertion  of  the  frog- 
stay.  The  base  looks  backwards,  and  is  divided  into  two  bulbous 
enlargements,  which  are  united  to  the  lateral  cartilages.  The 
summit  looks  forwards,  and  is  attached  to  the  plantar  surface  of 
the  OS  pedis  in  front  of  the  semilunar  ridge.  The  lateral  surfaces 
correspond  to  the  commissures  of  the  frog,  and  are  continuous 
with  the  inner  surface  of  the  lateral  cartilages.  The  sensitive 
frog  is  niade  up  of  an  external  layer  of  cuticular  structure,  the 


Sensitive  foot— solar  aspect. 
a.  Velvety  tissue  of  the  sole ;  b, 
That  of  frog. 


SENSITIVE   STRUCTURES    OF   THE   FOOT. 


551 


villi  of  which  secrete  the  horny  frog ;  below  this  is  a  layer  of 
capillary  blood-vessels ;  its  substance  is  made  up  of  connective 
tissue,  intermixed  with  yellow-fibro-cellular  tissue  of  a  peculiar 
elastic  nature,  which  used  to  be  described  as  fat. 

The  Coronary  substance,  or  coronary  band,  formerly  called 
the  coronary  ligament,  is  that  vascular  structure  Avhich  occupies 
the  cutigeral  groove  on  the  superior  border  of  the  wall.  It 
consists  of  a  dense  fibrous  mesh  or  band,  which  is  connected  with 
the  coffin  bone  and  extensor  tendon  by  the  medium  of  dense 
cellular  tissue,  Keposing  on  this  is  a  plexus  of  blood-vessels, 
which  is  covered  by  a  modification  of  the  true  skin,  containing 
numerous  papillae,  which  enter  the 
funnel-shaped  openings  in  the  crust, 
the  horn  of  which  is  thus  secreted. 

The  coronary  band  presents  along 
its  upper  border  a  narrow"  lip  or 
process — the  periojMc  ring — which 
secretes  the  horn  of  the  periople. 

The  Sensitive  lamina  (podo- 
phyllous  tissue)  are  the  continua- 
tion of  the  coronary  substance,  and 
are  attached  to  the  coffin  bone  by  a 
dense  fibrous  membrane,  in  which 
ramifies  the  vascular  plexus  emana- 
ting from  the  bone.  These  highly- 
organised  plates  are  interposed 
between,  and  firmly  attached  to,  the 
homy  lamine3  on  the  wall,  and  are 
covered  by  minute  papillae,  which 
secrete  the  horny  laminae  ;  on  their 
inferior  extremity  are  a  few  papillae,  which  help  to  secrete  the 
homy  sole. 

The  Sensitive  sole,  continuous  with  the  sensitive  laminae 
and  frog,  is  firmly  attached  to  the  coffin  bone ;  like  the  sensitive 
laminas,  it  is  made  up  of  a  fibro-vascular  membrane,  clothed  by 
a  continuation  of  the  corium,  which  is  covered  by  the  villi  which 
secrete 'the  horny  sole. 

For  the  circulation  of  the  foot,  see  pp.  417,  439;  for  its 
nerves,  pp.  511,  514. 


Sensitive  foot— lateral  view,    a,  Corc- 
nary  band ;  6,  Podophyllous  tissue. 


552  COMPARATIVE    ^STHESIOLOGT. 

COMPARATIVE    ^STHESIOLOGY. 

RUMINANTIA. 
The  concha  of  the  ear  is  widely  opened,  projects  outwards,  and  is  less  mobile 
than  that  of  the  horse ;  the  internal  and  middle  ears  present  no  feature  worthy 
of  note,  except  that  the  handle  of  the  malleus  is  more  curved.  The  tapetuiD 
lucidum  of  the  eye  is  of  a  golden  green  colour,  inclining  to  blue  at  the  circum- 
ference. In  all  the  domesticated  animals  the  gland  of  Harder  occurs  ;  and  in 
other  respects  generally  the  eye  of  the  ruminant  resembles  that  of  the 
solipede. 

The  hair  on  the  tail  of  the  ox,  like  that  of  the  ass,  is  long  only  at  the 
extremity,  where  it  forms  a  tuft.  About  the  frontlet— i.e.,  between  the  horns 
— the  hair  is  thick  and  curly,  but  in  a  degree  varying  in  different  breeds. 
The  wool  found  on  some  of  the  smaller  ruminants  may  be  regarded  as  a 
modification  of  hair. 

The  horns,  or  weapons  of  offence,  consist  of  a  layer  of  horn  tissue,  developed 
from  the  secretion  of  a  vascular  and  nervous  membrane  which  covers  the 
horn-core,  and  forms  at  its  base  a  circular  pad,  becoming  continuous  with  the 
dermis.  Both  the  membrane  and  the  pad  contain  keratogenous  tissue,  hence 
the  tissue  of  horns,  like  the  wall  of  the  horse's  hoof,  is  derived  from  two 
sources.  The  portion  of  the  horn  surrounding  the  pad  is  known  as  the  root, 
that  covering  the  core  the  body,  while  the  part  projecting  beyond  the  core  is 
the  point.  A  number  of  rings  appear,  surrounding  the  horn  just  above  its 
root,  which  are  rather  unreliable  indications  of  the  age  of  the  animal.  In 
shape  horns  vary  much  ;  in  the  bovidae,  the  typical  form  is  crescentic,  with 
the  convexity  turned  more  or  less  downwards  and  outwards  ;  in  the  ovidse, 
where  developed  horns  are  less  general,  they  are  usually  curved  spirally,  some- 
times assuming  a  very  graceful  curve,  the  first  bend  being  with  the  convexity 
outwards  and  forwards  ;  in  the  goat  they  are  closer  together,  and  more 
perpendicular,  being  slightly  curved,  with  the  convexity  inwards ;  all  these 
forms  are  subject  to  great  variation,  some  species  of  ruminants,  as  the 
camelidae,  being  altogether  without  horns,  while  in  others  their  development 
is  enormous. 

Animals  possessing  horns  of  the  above  type  are  classed  as  cavicornia,  or 
hollow-horned.  The  horns  of  deer  (antlers)  differ  from  these,  in  being  formed 
of  solid  bone,  in  having  branches,  and  being  deciduous,  falling  off  every  year 
to  be  replaced  by  new  ones. 

The  hoof  is,  of  course,  divided  into  two  parts,  one  for  each  digit,  each  part 
resembling  in  shape  the  distal  phalanx.  Their  general  structure  resembles 
that  of  the  horse's  hoof,  but  the  frog  is  little  developed.  A  small  horny 
projection  appears  on  each  side  of  the  posterior  aspect  of  the  fetlock  ;  these 
are  rudimentary  hoofs,  each  containing  a  small  bone  disconnected  with  the 
skeleton. 

OMNIVORA 

In  the  hog  the  concha  is  large,  but  variable  in  its  arrangement,  being 
c?ometimes  erect  sometimes  flaccid.  In  connection  with  the  eye  the  gland  of 
Harder  exists.     The  skin  is  thick,  often  destitute  of  pigment,  and  has  a  very 


RODENTIA.  553 

"thick  subjacent  layer  of  fat.  The  amount  of  hair  on  the  skin  varies  greatly, 
but  appears  to  decrease  in  proportion  to  the  domesticity  of  the  animal,  the 
wild  boar  being  provided  with  a  comparatively  thick  coat.  The  hairs  are 
thick  and  strong,  being  commonly  known  as  bristles.-  In  a  general  sense  the 
hoofs  resemble  in  form  those  of  the  ruminant,  but  they  consist  of  four 
pieces  on  each  extremity.      See  Fig.  32. 

CAENIVOEA. 

The  conchal  cartilage  in  the  dog  is  extremely  variable,  both  in  shape  and 
size,  according  to  the  breed,  but  in  most  breeds  it  folds  downwards,  forming 
the  drop,  or  flap,  which  serves  to  protect  the  cavity  cf  the  external  ear  from 
the  intrusion  of  foreign  matters.  In  the  cat,  and  in  fact  in  the  felidce 
generally,  the  concha  is  broad,  short,  and  erect,  with  the  opening  turned 
forwards. 

The  globe  of  the  eye  is  much  more  spherical,  while  the  iris  is  of  various 
modified  shades  of  yellow.  The  pupil  is  circular,  and  the  tapetum  lucidum 
of  a  bluish  white.  In  .some  features  the  eye  of  the  cat  differs,  the  pupil  being 
circular  only  when  fully  dilated ;  when  contracted  it  appears  as  a  narrow 
vertical  slit ;  the  iris  has  a  greenish  lustre,  while  the  tapetum  lucidum  is 
golden  yellow. 

The  sudoriferous  glands  are  extremely  minute  and  difficult  to  find,  excepting 
about  the  region  of  the  nose  and  digital  pads.  The  latter  are  callous  thicken- 
ings of  the  epidermis,  upon  which  the  animal  walks.  The  distal  phalanges 
are  covered  by  horn,  which  projects,  curving  outwards  and  downwards  to  form 
the  claws.  As  we  have  already  seen,  the  claws  are  retractile  in  the  cat,  where 
they  are  also  sharp,  and  serve  chiefly  as  weapons  of  ofi"ence.  '  In  the  dog  the 
•claws  are  virtually  fixed  and  blunt,  becomiug  worn  by  constant  locomotion 
.and  scratching. 

No  rule  can  be  given  as  to  the  nature  of  the  hair  in  dogs,. as  it  differs  greatly 
in  length,  texture,  and  colour.  In  the  cat  it  is  short,  sleek,  and  furry,  and  in 
colour  equally  variable.  The  touch-hairs,  or  whiskers,  situated  at  the  sides  of 
the  nose,  are  well  marked  in  the  cat,  and  are  usually  white  in  hue  ;  the  tail  is 
generally  covered  by  hai'"  nearly  as  short  as  that  on  the  rest  of  the  body. 


KODENTIA. 

The  concha  of  the  ear  is  large  and  very  long  in  the  rabbit,  and  may  be  either 
•erect  or  pendent,  but  most  usually  it  is  the  former.  There  are  no  puncta 
lachrymalia J  the  lachrymal  gland  and  membrana  nic(;itans  are  both  large. 
The  rabbit  tribe  is  remarkable  for  including  a  large  number  of  albinos  or 
individuals  devoid  of  pigmentary  tissue  ;  the  result  of  this  is  perfect  whiteness 
of  hair  and  skin,  apd  redness  of  the  iris,  the  latter  being  due  to  the  thick  plexus 
of  blood-vessels  contained  therein,  which  is  displayed  by  the  absence  of 
pigment. 

The  claws  somewhat  resemble  those  of  the  dog,  but  they  are  better  adapted 
for  scraping  the  soil,  the  animal  being  naturally  a  burrower. 


554  COMPARATIVE    ^STHESIOLOGY. 


AVES. 


Birris  have  no  concha,  tlie  external  ear  comprising  only  the  auditory  meatus^ 
This  deficiency  in  the  apparatus  for  collecting  sound  is  compensated  for  in  the- 
large  size  of  the  labyrinth.  The  cochlea  is  not  shell-shaped,  but  merely  a  bent 
tube ;  the  semicircular  canals  are  proportionally  very  large.  The  auditory 
ossicle's  are  represented  by  a  single  bone,  called  the  columella,  which  perhaps 
represents  the  stapes,  attached  by  processes  of  cartilage  to  the  tympanic 
membrane.  Owen  considers  these  cartilages  the  representatives  of  the 
mammalian  malleus,  Huxley  that  they  represent  the  incus,  while  the  latte 
authority  holds  that  the  malleus  is  represented  by  the  os  quadratum.  The 
Eustachian  tube  is  large  and  osseous  in  structure. 

The  eye  in  birds  is  very  large,  and  only  slightly  movable.  The  sclerotic 
coat  contains  anteriorly  a  ring  of  imbricated  osseous  scales  varying  in  number 
from  twelve  to  twenty.  Not  unfrequently  it  becomes  ossified  posteriorly 
forming  an  osseous  sheath  round  the  optic  nerve  The  pecten  is  a  vascular 
membrane  stretching  from  the  porus  opticus  into  the  substance  of  the  vitreous 
humour.  The  choroid  coat  is  always  black,  and  the  pupil  round  ;  the  iris  is 
said  to  contain  striated  muscular  fibre.  The  membrana  nictitaris  is  well 
developed,  and  moved  by  two  muscles.  The  lachrymal  and  Harderian  glands 
are  present,  but  the  Meibomian  glands  are  wanting. 

The  exoskeleton  consists  of  the  skin,  modified  in  places  into  horn  or  scales, 
and  elsewhere  covered  by  structures  peculiar  to  the  class — the  feathers  or 
plumage ;  these  are  chiefly  of  two  kinds,  the  quill-feathers  and  the  ciothinff 
feathers,  the  most  rudimentary  of  the  latter  being  known  as  "down."  A  quill- 
feather  consists  of  two  principal  portions — the  quill  {calamus)  and  the  vane 
(vexillum) ;  the  quill  is  continuous  with  the  central  shaft  called  the  rachis,  the 
two  forming  the  stem  or  scapus  of  the  feather.  Projecting  outwards  from  the 
stem  on  each  side  are  a  large  number  of  pointed  and  very  flexible  barbs,  these 
again  bearing  still  smaller  processes  or  barbules.  At  either  end  of  the  quill  is 
a  small  opening  or  umbilicus,  and  inside  the  barrel  is  contained  a  pulp,  which 
in  young  feathers  is  very  vascular,  the  vessels  entering  by  the  proximal  umbil- 
icus, which,  along  with  part  of  the  quill,  is  buried  in  a  papillated  follicle  of  the 
skin  ;  at  the  base  of  the  shaft  a  second  rudimentary  shaft  is  usually  formedy 
which,  however,  may  be  represented  by  a  mere  tuft  of  down.  The  smaller 
feathers  are  constructed  on  the  same  general  principles  ;  they  cover  the  body, 
the  upper  part  of  the  legs,  and  the  head,  while  the  larger  feathers  and  quills 
are  confined  to  the  wings  and  tail. 

The  longest  quiU-feathers  are  those  arising  from  the  hand,  called  the 
primaries  J-  those  arising  from  the  distal  part  of  the  fore-arm  are  the  second- 
aries; while  the  tertiaries  axe  those  which  spring  from  the  proximal  part  of 
the  same.  The  rudimentary  pollex  carries  some  feathers  which  form  the 
alula  or  bastard  wing.  The  scapularies  are  feathers  covering  the  scapula  and 
humerus.  The  wing  coverts  axe  rows  of  small  feathers  covering  the  bases  of 
the  larger  ones  ;  they  are  described  aa  three,  the  greater,  the  lesser,  and  the 
inferior.  The  quill-feathers  of  the  taU  are  called  the  redrices;  they  hava 
considerable  mobility,  and  their  bases  are  covered  by  a  row  of  tail-coverts. 


AVES.  555 

The  skin  becomes  homy  where  it  covers  the  rostrum  or  beak,  and  in  some 
t)irds  at  the  base  of  the  same,  it  forms  scales  round  the  nostril ;  or  this  part 
may  have  a  naked  or  waxy  appearance,  which  is  known  as  the  cere.  Below  the 
tarsal  joint  the  extremity  is  usually  covered  with  homy  scales  or  plates,  but 
some  breeds  of  domesticated  birds  are  "  feathered  to  the  ground."  The  pedal 
digits  of  the  natatores  in  each  limb  are  joined  by  a  membrane,  which  is 
covered  vnth.  scaly  skin,  forming  the  wcb-foot.  In  the  domestic  fowl  the  claws 
are  blunt  and  very  strong,  that  bird  being  a  good  example  of  the  order 
Easores,  or  scrafchers.  The  glands  of  the  skin  are  few,  but  in  many  birds,  and 
notably  in  aquatic  species,  there  is  a  large  gland  in  the  skin  of  the  uropygium, 
or  basis  of'  the  tail ;  this  gland  seeretes  an  oily  sebaceous  fluid,  which  is 
employed  by  the  animal  in  drebsing  or  preening  its  feathers.  The  combs  or 
wattles^  which  are  the  red  or  sometimes  blue  processes  formed  about  the  heads 
of  certain  birds,  are  very  vaacular  antf  «iften  erectile  structures,  appendages  of 
the  integument. 


CHAPTER  VIIL 

EMBRYOLOGY. 

As  this  branch  of  the  subject  is  better  studied  from  a  physiological 
point  of  view,  we  must  refer  the  student  to  some  able  work  on 
physiology  for  a  description  of  the  changes  in,  and  development 
of,  the  fecundated  germ  of  the  future  animal.  Our  few  remarks, 
for  the  most  part,  apply  to  the  fully,  or  nearly  fully,  developed 
foetal  animal. 

As  we  have  previously  seen,  the  ovum  is  the  germ  of  the 
future  animal,  while  the  fecundating  principle  is  the  spermato- 
zoon. From  the  period  of  fecundation  to  that  of  parturition,  oi 
birth  of  the  young,  the  interval  is  said  to  be  that  of  utero-gesta- 
Hon.  This  interval  differs  in  different  classes  of  animals,  but  in 
the  same  class  it  persists  with  singular  uniformity,  the  variations 
being  small.  The  period  of  utero-gestation  in  the  mare  is  48 
weeks;  in  the  cow,  40  ;  in  the  sheep,  21,  or  22  ;  in  the  sow, 
16,  or  17  ;  in  the  bitch,  9  ;  and  in  the  rabbit,  about  4  weeks. 

In  its  early  stages  of  development  the  fecundated  ovum  is 
known  as  the  embryo  ;  in  the  later  stages  it  is  called  the  foetus  ; 
but  the  exact  condition  at  which  this  change  of  name  occurs  is 
indeterminate.  The  foetus  occupies  the  cavity  of  the  uterus, 
the  neck  of  that  organ  being  closed  during  gestation  by  the 
Nabothian  glands. 

OVUM    AFTER    FECUNDATION. 

The  primary  changes  undergone  by  the  fecundated  ovum, 
interesting  as  they  are,  can  be  merely  alluded  to  here.  By 
repeated  fusion  of  the  vitelline  substance  there  arises  a  cellular 
material  called  the  emhryogenic  tissue,  or  blastoderm,  out  of 
which  the  body  of  the  embryo  is  formed.  This  tissue  divides 
into  three  layers,  an  outer,  a  middle,  and  an  internal,  called 
556 


PLACENTA.  55T 

respectively  the  epiblast,  mesoblast,  and  hypoblast.  From  the 
epiblast  become  developed  the  epidermis  and  its  appendages,  and 
the  cerebro-spinai  axis,  from  the  hypoblast  the  mucous  membrane 
of  the  alimentary  canal,  while  the  mesoblast  gives  rise  to  the 
intervening  organs  and  tissues. 

A  linear  indentation,  the  primitive  groove,  appears  on  the 
epiblast,  and  below  and  coincident  with  this  the  notochord,  which 
indicates  the  position  of  the  vertebral  column,  becomes  formed. 

The  chief  appendages  and  coverings  associated  with  foetal  life 
are  the  umbilical  sac,  the  amnion,  chorion,  and  allantois,  the 
placenta,  and  the  umbilical  cord. 

The  outer  covering  of  the  fcetus  is  the  chorion,  a  membrane 
derived  from  the  blastoderm  and  reflected  over  the  foetus  ;  the 
placenta  is  formed  by  the  connection  of  this  covering  with  the 
mucous  membrane  of  the  uterus.  The  inner  covering  is  the 
amnion,  which  contains  a  fluid,  the  liquor  amnii.  The  allantois 
or  urinary  vesicle  is  regarded  as  taking  its  origin  from  the 
primitive  intestine.  Becoming  vesicular  in  form  to  it  proceed 
the  ducts  of  the  Wol-§ian  bodies,  or  primordial  kidneys. 

The  umbilical  sac  proceeds  from  the  blastoderm ;  it  covers  the 
yelk,  and  like  the  allantois  is  not  included  in  the  amnion. 


PLACENTA. 

The  blood  of  the  foetus  becomes  purified,  and  charged  with,  the 
materials  of  nutrition,  by  being  brought  into  close  connection  with 
the  blood  of  the  mother,  and  this  process  is  achieved  in  a  struc- 
ture called  the  placenta,  an  organ  which  contains  capillary  plexuses 
derived  from  the  umbilical  arteries  of  the  foetus,  and  others  from 
the  uterine  arteries  of  the  mother;  it  is  situated  between  the 
mucous  membrane  of  the  uterus  and  the  external  membranous 
sac,  the  chorion,  which  completely  envelops  the  foetus,  to  both 
of  which  structures  it  is  attached. 

The  placenta  assumes  a  variety  of  forms  in  the  various  classes 
of  animals.  In  the  mare  and  sow  it  is  diffused — i.e.,  it  consists 
of  villi  scattered  over  nearly  the  whole  outer  surface  of  the  chorion, 
and  received  into  crypts  or  correspondiug  recesses  in  the  uterine 
mucous  membrane.  In  the  ruminant  the  placental  villi  are 
collected  into  groups,  forming  a  number  of  rounded  or  ovoid  objects 
termed,  cotyledons,  hence  this  placenta  is  said  to  be  polycoty- 
ledonary.       However   in  the  Camelidce — "The  foetal  villi  are 


558 


EMBETOLOGY. 


scattered  evenly  over  the  chorion,  so  that  the  placenta  is  diffuse." 
(Huxley),  In  carnivora  the  villi  are  collected  in  a  mass  which 
assumes  the  form  of  a  belt,  surrounding  the  chorion,  and  hence 
called  a  zonary  placenta.  In  rodentia  the  placenta  is  discoid, 
the  villi  being  assembled  in  a  more  or  less  circular  mass. 

The  placenta  is  found  in  most  orders  of  mammals,  and  in  tnem 
alone  ;  its  presence  or  absence  has  led  to  the  separation  of  the 
class  mammalia  into  a  placental  and  an  implacental  division. 


Foetus  of  the  Cow,  with  its  membranes,    a  a,  Placenta  ;  6  h,  Chorion  with  the  AUantois  adherent 
to  its  inner  surface  ;  c  c,  Amnion  seen  through  outer  covering  ;  d,  foetus  seen  through  its  coverings. 


UMBILICAL    CORD. 

This  structure  is  the  medium  of  connection  between  the  foetus 
and  the  placenta,  reaching  from  the  latter  to  the  umbilical  open- 
ing in  the  linea  alba.  It  consists  mainly  of  the  umbilical  vessels, 
one  vein,  and  two  arteries,  and  superiorly  contains  the  urachus, 
a  foetal  tube  continuous  with  the  bladder. 


CIRCULATION    OF    THE    FCETUS. 


559 


CIRCULATION    OF    THE    FCETUS. 

In  the  fcEtus  there  is  a  direct  communication  between  the 
right  and  left  auricles,  by  the  foramen  ovale  in  the  interauricular 
septum  ;  and  in  man  the  large  Eustachian  valve,  situated  at 
the  anterior  border  of  the  posterior  vena  cava,  at  its  entrance 
into  the  auricle,  directs  the  blood  from  the  posterior  vena  cava 
through  the  foramen  ovale  into  the  left  auricle;  as  we  have 
before  remarked,  the  presence  of  this  valve  in  quadrupeds  is  very 
doubtful.  Another  difference  between  the  foetus  and  adult  is 
the  presence  of  a  communicating  branch  between  the  pulmonary 
artery  and  posterior  aorta,  called  the  ductus  arteriosus.     There 


Fio.  217. 
Fa'.oB  of  the  Bitch,  with  its  membranes,   a  a,  Uterine  placenta ;  6  b.  Foetal  placenta ;  c  c,  Chorion  ■ 
d  a.  Amnion  seen  through  former  ;  e  e,  Fcetna  visible  throcgh  iU  coverings. 

are  two  large  arteries,  the  umbilical  or  hypogastric,  which  arise 
from  the  internal  iliacs,  pass  along  the  sides  of  the  bladder  to  its 
fundus,  and  out  of  the  umbilical  opening,  being  continued  along 
the  umbilic&,l  cord  to  the  placenta;  in  their  course  down  the 
cord  they  wind  spirally  round  the  umbilical  vein  Finally,  the 
umbilical  vein  leaves  the  placenta,  passes  up  the  cord,  and  enters 
the  umbilicus,  running  along  the  floor  of  the  abdomen,  to  reach 
the  liver,  where  it  joins  the  vena  porta.  We  may  now  proceed 
to  trace  the  course  of  the  foetal  circulation. 

The  purified  blood  leaves  the  placenta  by  the  umbilical  vein, 
which  is  formed  by  the  junction  of  numerous  radical  branches,  and 
passes  along  the  umbilical  cord,  accompanied  by  the  two  arteriea* 


560 


"EMBRYOLOGY. 


on  entering  the  s.hdomcn,  it  passes  forward  along  the  floor  of  the 
abdominal  cavity,  covered  by  peritoneum  ar.d  thus  arrives  at  the 
liver ;  it  joins  the  portal  vein,  its  blood  thus  gaining  the  hepatic 
veins,  and  afterwards  the  posterior  vena  cava,  where  it  mingles  with 
the  venous  blood  from  the  posterior  region.  The  mixed  blood  is 
conveyed  by  the  posterior  cava  into  the  right  auricle,  and  passes 
directly  through  the  foramen  ovale  into  .the  left  auricle  ;  from  the 
left  auricle  it  enters  the  left  ventricle,  and  by  it  is  forced  into  the 
aorta  ;  the  major  part  passing  into  the  anterior  aorta,  is  distributed 
to  the  head  and  fore  extremities  ;  the  remainder  passes  into  the 
posterior  aorta. 


Fio.  218. 
Trunk  of  a  fuUy-develop«d  foetus— opened  from  the  left  side  to  show  the  circulation,  o,  Um- 
bilical cord,  cut  and  ligatured  ;  6  b,  Umbilical  vein  ;  c.  Portal  vein  ligatured  ;  d  d,  Posterior  vena 
cava ;  e  e.  Openings  of  hepatic  veins ;  /,  Diaphragm  cut  and  reflected ;  g,  Heart ;  h.  Pulmonary 
artery  ;  i,  Common  aorta ;  i',  Anterior  aorta  ;  i"  i".  Posterior  aorta  ;  k.  Ductus  arteriosus  ;  i.  Left, 
I',  Eight  umbilical  arteries  ;  m,  Bladder ;  n,  Urachus  ;  o  o,  Thymus  gland. 

Venous  blood  is  returned  from  the  anterior  region  to  the  right 
auricle  by  the  anterior  vena  cava,  and  passes  directly  into  the 
right  ventricle  along  with  a  small  portion  of  the  blood  from  the 
posterior  vena  cava  ;  the  right  ventricle  propels  it  through  the 
pulmonary  attery,  from  which  only  a  small  portion  passes  into  the 
impervious  lungs,  to  be  returned  to  the  left  auricle  by  the  pul- 
monary veins,  the  greater  part  going  through  the  ductus  arteriosus 
into  the  posterior  aorta,  where  it  becomes  mixed  with  a  portion 
of  the  blood  from  the  left  ventricle.  In  the  posterior  aorta,  it 
flows  backwards  to  supply  the  posterior  extremities  and  abdominal 
viscera  ;  the  chief  portion,'  however,  on  arriving  at  the  termina- 
tion of  the   posterior  aorta,  enters  the  umbilical  arteries,  and  by 


DEVELOPMENT    OF    THE    FCETUS.  561 

them  is  returned  to  the  placenta  to  be  purified.  At  birth,  when 
respiration  has  been  established,  the  placental  circulation  is  cut 
ofif,  the  foramen  ovale  rapidly  closes  up,  leaving  the  fossa "ovalis  ; 
the  ductus  arteriosus  contracts,  and  together  with  the  umbilical 
arteries  and  vein,  becomes  obliterated. 

The  consideration  of  these  facts  will  show  that  the  foetus  is 
nourished  by  blood  less  perfectly  arterialised  than  that  of  the 
adult,  the  blood  becoming  mixed  in  the  liver,  in  the  heart,  and 
in  the  posterior  aorta  by  means  of  the  ductus  arteriosus.  It 
should  be  borne  in  mind  that  the  blood  which  supplies  the 
posterior  regien  is  less  pure  than  that  supplying  the  head  and 
anterior  region ;  this  accounts  for  the  fact  that  at  birth  the 
posterior  parts  of  the  frame  are  less  developed  than  the  anterior. 
Development  of  the  Fcetus. 

The  following  facts  and  measurements  derived  from  the 
observations  of  Gurlt,  Leyh,  Franck,  and  others,  may  be  useful 
in  determining  the  age  of  the  foetus  or  embryo. 

To  facilitate  the  study  of  the  development  of  the  foetus,  the 
time  which  elapses  between  conception  and  birth  has  been  divided 
into  seven  periods  as  follows  : — 

I,  Period. — Includes,  in  all  the  domesticated  mammals,  the 
first  and  second  weeks  after  conception.  The  ovum  lies  free  in 
the  uterus.  In  the  dog  it  measures  about  one  line  in  length. 
The  chorion  and  amnion  can  be  made  out. 

II.  Period. — Includes,  in  the  horse  and  ruminant,  the  3rd 
and  4th  weeks ;  in  the  pig,  the  3rd  and  half  of  the  4th  week ; 
in  caruivora,  the  3rd  week. 

(a)  Horse. — At  28  days  the  embryo  is  p,  little  over  |  inch 
long.     The  division  into  head,  trunk,  and  limbs  is  indicated. 

(6.)  Ox. — At  28  days,  the  embryo  has  a  length  of  |-  inch, 
and  corresponds  in  its  development  to  the  sheep's  embryo  of  25 
days. 

(c.)  Sheep. — Theembryo  of  the  sheep,  at  18  days,  has  a  length 
of -|^  inch.  At  23  days,  indications  of  the  feet  appear.  At  25 
days,  it  has  a  length  of  -|  inch ;  indications  of  the  eyes,  ears,  and 
tail  are  present ;  the  intestine  exists  as  a  tube  connected  with 
the  umbilical  vesicle  ;  the  Wolffian  body  is  well  developed. 

(d.)  Pig. — The  pig's  embryo,  at  21  days,  has  a  length  'of  about 
J  inch;  at  24  days,  1  to  f  inch.  The  umbilical  vesicle  has, 
reached  its  maximum  size. 

2o 


562  EMBRYOLOGY. 

{e.)  Carnivora. — The  villi  appear  on  the  chorion,  and  become 
attached  to  the  mucous  membrane  of  the  uterus.  At  18 
days,  the  embryo  of  the  dog  has  a  length  of  about  ^  inch  ;  the 
primitive  groove  and  chorda  dorsalis  are  present.  At  19  or  20 
days,  the  heart  is  present  as  an  S-shaped  tube  ;  the  intestine 
begins  to  form.  At  21  days,  indication  of  the  eyes,  ears,  and, 
"Wolffian  body  are  present ;  the  limbs  are  present  as  small 
blunt  processes. 

III.  Period. — Includes,  in  the  horse  and  ox,  the  5th  to  the 
8th  week  ;  in  the  sheep  and  gOat,  the  5th,  6th,  and  first  half  of 
the  7th  week  ;  in  the  pig,  the  last  half  of  the  4th,  the  5th,  and 
first  half  of  the  6th  week ;   in  carnivora,  the  4th  week. 

{«.)  Hors". — The  horse's  embryo^  at  6  weeks,  has  a  length  of 
1|-  incii.  At  7  weeks,  2  inches;  and  at  8  weeks,  2|-  inches;  the 
thoracic  and  abdominal  cavities  are  closed. 

(6.)  Ox. — At  6  weeks,  the  embryo  is  ^  inch  in  length,  and 
corresponds  to  the  22-2 o  days-old  dog's  embryo.  At  7  weeks, 
it  is  about  1^  inch  in  length;  the  udder  begins  to  form  ;  the 
kidneys  and  ureters  are  present.  At  8  weeks,  the  embryo  is  from 
2  inches  to  2|-  in  length. 

(c.)  Sheep. — At  the  5  th  week,  the  embryo  has  a  length  of 
1  inch,  and,  in  development,  corresponds  to  the  25  days-old 
dog's  embryo, 

(d.)  Pig. — At  28  days,  the  embryo  has  a  length  of  1  inch. 
At  37  days,  2-1  inches. 

(e.)  Carnivora. — At  22-23  days,  the  embryo  has  a  length  of 
about  "I  inch  ;  mouth-groove,  nostrils,  lungs,  trachea,  and  larynx 
are  present ;  the  anus  is  still  closed  ;  Wolffian  body  well  formed  ; 
•limbs  about  one  line  in  length.  At  25  days,  the  thorax  is  closed, 
and  the  abdominal  cavity  almost  closed.  At  26-28  days,  the 
embryo  is  about  1|^  inch  in  length  ;  all  organs  are  more  or 
less  distinctly  marked. 

IV.  Period. — Includes,  in  the  horse,  the  9th  to  the  IStb 
week;  in  cattle,  the  9th  to  the  12th  week;  in  the  sheep  and 
goat,  the  last  half  of  the  7th,  the  8th,  and  the  9th  weeks;  in 
pigs,  the  last  half  of  the  6  th,  the  7th,  and  first  half  of  the  8th 
week  ;  in  carnivora,  the  5  th  week. 

(a.)  Horse. — At  the  9th  week,  the  embryo  measures  3^  inches  ; 
the   external   ears    are  very  small  ;  the  Wolffian  body,   genital 


DEVELOPMENT   OF   THE   FffiTUS.  563 

glands,  kidneys,  and  suprarenal  capsules  are  present.  At  10 
^•eeks,  the  embryo  measures  Sf  inches;  the  internal  and 
external  genital  organs  are  formed.  At  11  weeks,  the  embryo 
measures  4  ^  inches.  At  1 2  weeks,  4|-  inches ;  ,and  at  1 3  weeks 
5|-  inches. 

(6.)  Ox. — At  9  weeks,  the  embryo  measures  almost  3^  inches. 
At  10  weeks,  3f  inches.  At  11  weeks,  4f  inches,  and  its 
development  corresponds  to  that  of  the  horse's  embryo  of  the 
same  age ;  mouth-groove  and  nostrils  are  closed  by  a  thin  mem- 
brane ;  the  divisions^  of  the  stomach  are  present.  At  1 2  weeks, 
the  embryo  measures' 5-|  inches. 

(c.)  Sheep  and  Goat. — At  8  weeks,  the  length  of  the  embryo 
is  about  2  inches.  At  9.  weeks,  3f  inches  ;  the  nostrils  are  still 
closed. 

{d.)  Pig, — Length  of  embryo  in  the  8th  week  is  3^  inches. 

(e.)  Carnivora. — Length  of  embryo  in  the  5  th  week  is  2-| 
inches. 

V.  Period. — Includes,  in  the  horse,  the  14th  to  the  22nd 
week;  in  the  ox,  the  13th  to  the  20th  ;  in  the  sheep  and  goat, 
the  10th  to  the  13th;  in  the  pig,  the  last  half  of  the  8th,  the 
4Hh,  and  the  10th  week;  in  carnivora,  the  6th  week. 

(a.)  Horse. — During  this  period  the  embryp  increases  from  5-| 
inches  to  14f  inches.  At  17  weeks,  the  first  hair  appears  on 
the  lips.  At  22  weeks,  the  lips,  eyelids,  and  point  of  tail  are 
provided  with  hair. 

(6.)  Ox. — The  embryo  increases  from  of  inches  to  12f.  At 
18  weeks,  the  hair  appears,  and  the  testicles  descend  into  the 
scrotum. 

(c.)  Sheep  and  Goat. — At  the  end  of  this  period  the  embryo 
measured  C-f  inches ;  hair  is  still  wanting. 

(d.)  Pig. — The  embryo  measures  5^  inches. 

(e.)  Carnivora. — The  embryo  has  a  length  of  3-^  inches. 

VL  Period. — Includes,  in  the  horse,  the  23rd  to  the  34th 
week;  in  cattle,  the  21st  to  the  32nd  week  ;  in  the  sheep  and 
goat,  from  the  last  half  of  the  13th  to  the  18th  week;  in  th^ 
pig,  from  the  11th  to  the  first  half  of  the  15th  ;  in  the  dog,  the 
7th  and  8th  weeks ;  in  the  cat,  to  the  end  of  the  7th  week. 

(a.)  Horse. — The  embryo  grows  about  one  inch  weekly,  and 
■at  the  end  of  the  period  has  a  length  of  about  27  inches.     The 


564  EMBRYOLOGY. 

hair  appears  on  the  crest  aud  back.  The  testicles  lie  near  the- 
abdominal  ring. 

(b.)  Ox. — The  embryo  at  the  end  of  32  weeks  measures  about 
25  inches. 

(c.)  Sheep  and  Goat. — The  embryo  has  a  length  of  from  10 
to  13  inches. 

(d)  Pig. — The  embryo  measures  about  7  inches  in  length. 

(e.)  Carnivora. — The  dog's  embryo  measures  about  5  inches ;_ 
the  cat's  embryo,  4  inches.  The  body  is  covered  with  hair,  and 
the  claws  are  present.  The  eyelids  are  closed,  and  the  testicles 
are  still  in  the  abdomen. 

VII.  Period. — Includes,  in  tlie  horse,  the  3oth  to  the  48th 
week  ;  in  cattle,  the  33rd  to  the  40th  week;  in  the  sheep  and 
goat,  the  19th  to  the  21st  or  22nd  week  ;  in  the  pig,  the  last 
half  of  the  15th  to  the  16th  or  l7th  week;  in  dogs,  the  9th 
week ;  and  in  cats.,  the  8th  week.  In  all  animals  it  reaches  up- 
to  the  time  of  birth. 

(a.)  Horse. — The  foetus  attains  at  the  end  6i  this  period  a 
length  of  over  a  metre  (3  feet)  ;  it  is  completely  covered  with 
hair,  and  the  testicles  pass  into  the  scrotum.  The  inguinal  ring- 
is  very  wide,  and  slight  hernia  is  generally  present. 

(6.)   Ox. — The  foetus  measures  atout  32  inches. 

(c.)  Sheep. — The  foetus  has  a  length  of  about  18  inches. 
Goat. — The  foettis  measures  about  1 3  inches  ;  if  only  one  foetus 
is  present,  18  inches. 

(d.)   Pig. — The  fostus  has  a  length  of  10  inches. 

(e.)  Carnivora. — The  foetus  measures  about  7  inches.  The 
cat's  foetus,  about  5  inches. 


APPENDIX. 


No.  I. 
GENERAL  DIRECTIONS  FOR  DISSECTION. 

Compiled  chiefly  from  Chauveau's  "  Traite  d'Anatomie  Comparie  d£S 
Animaux  Domestiques." 

THE  ARTICULATIONS  AND  LIGAMENTS. 

In  order  to  prepare  the  articulations,  the  student  should  select  young,  in 
pi'eference  to  subjects  advanced  in  age,  because  in  the  former  the  density 
of  the  cellular  tissue  is  less  than  in  the  latter  As  th'e  ligaments  are 
prepared  with  difficulty  when  their  external  surface  is  dried  up,  care 
should  be  taken  to  keep  them  protected  from  the  air  until  the  time  to 
dissect  them,  by  covering  them  with  wet  linen  rags,  or  with  the  hide  of 
the  animal. 

It  is  convenient  to  separate  the  articulation  which  one  wishes  to 
study,  by  cutting  the  bones  at  a  short  distance  from  the  articulatory 
surfaces.  The  handling  of  the  piece  is  thus  more  easy,  and  the  dissec- 
tion is  made  under  more  favourable  conditions. 

It  is  important  to  take  as  much  care  as  possible  of  the  muscles  which 
surround  the  ■  articulations,  so  as  to  be  able  to  study  their  connections 
with  the  ligaments.  If  it  is  absolutely  necessary  to  take  away  the 
muscles,  t^eir  attachments  shoitld  be  preserved. 

Study  first  the  capsular  ligaments,  and  then  remove  them  so  as  to 
display  the  funicular  bands.  The  latter,  in  their  turn,  are  to  be  sacrificed 
so  as  to  expose,  by  means  of  difierent  sections,  the  interosseous  ligaments, 
if  any  exist.  Separate  at  last,  in  a  complete  manner,  the  two  articular 
surfaces,  laying  them  bare,  and  then  examine  their  conformation. 

The  synovial  membranes,  with  their  difierent  cul-de-sacs,  being  a  very 
important  subject  of  study  with  reference  to  the  diagnosis  and  treatment 
of  certain  articular  diseases,  the  student  is  recommended  to  preserve  a 

565 


566  APPENDIX. 

special  piece  or  preparation  for  the  study  of  those  serous  membranes. 
He  may  also  very  easily  inject  their  interior  with  plaster  of  Paris,  or 
with  tallow,  coloured  black,  so  as  to  distend  their  cul-de-sacs,  and  favour 
the  study  of  theii'  connections  with  the  ligaments,  tendons,  or  muscles. 


THE  MUSCLES. 

Choice  of  a  Svhject. — Ii  a,  number  oi  subjects  are  at  the  disposal  of  the 
student,  so  that  he  has  it  in  his  power  to  make  a  choice,  he  should  give 
the  preference  to  those  in  which  the  muscular  system  is  well  dcvelopedj 
avoiding  however  very  fat  animals.  Subjects  of  small  or  middle  size  are 
always  more  convenient  than  those  having  great  masses  of  muscle  and  fat. 
Asses  and  mules,  when  they  are  very  lean,  show  the  muscular  system. 
very  distinctly. 

Position  of  the  Subject. — It  is  important  to  place  the  subject,  imme- 
diately after  death,  in  a  convenient  position,  as  cadaveric  rigidity 
preserves  it.  Without  this  precaution,  the  different  parts  of  the  body  of 
the  animal  may  take  an  inconvenient  attitude,  and  all  attempts  to  rectify 
the  position  will  be  for  some  time  futile,  especially  in  animals  of  greac 
size. 

The  subject  may  be  placed  in  three  different  positions  : — 

1.  The  animal  is  placed  in  the  first  position  when  it  is  laid  upon  its 
oack,  and  the  four  extremities  are  raised  in  the  air,  and  supported  by- 
means  of  cords  or  ropes  fixed  to  the  pasterns  and  passed  through  movable 
rings,  which  are  fixed  to  the  extremity  of  four  upright  bars  or  posts  at 
the  comers  of  the  table  upon  which  the  animal  is  laid.  The  head  passes 
over  the  end  of  the  table,  and  rests  upon  a  stool,  on  a  lower  level,  so 
that  the  neck  may  not  be  twisted. 

2.  To  place  the  animal  in  the  second  position,  it  is  turned  upon  its 
belly,  the  extremities  extended  upon  the  table,  and  the  head  supported 
between  two  upright  bars,  by  means  of  a  rope  passed  under  the  jaw. 

3.  The  subject  is  said  to  be  in  the  third  position  when  it  reposes  or* 
its  side. 

As  far  as  possible  the  skin  should  not  be  removed,  except  from  thosb 
regions  which  are  to  be  dissected  at  the  time.  If  it  can  be  done,  tiie 
student  should  take  the  precaution  of  wrapping  up  the  parts  with  clotns 
wet  with  some  preservative  fluid,  to  prevent  the  drying  up  of  the  apo- 
neuroses and  the  superficial  muscles. 

To  dissect  a  muscle,  raise  the  aponeurosis,  or  the  other  muscles  whicJ; 
cover  it,  and  dissect  off  the  cellular  tissue  which  enwraps  it,  the  fat,  and 
after  ascertaining  their  names,  the  glands,  vessels,  and  nerves  lodged  in 
the  interstices.     Dissect  the  aponeurosis  in  strips,  making  the  scalpel  glide 


APPENDIX.  567 

laetween  the  fibrous  layers,  holding  the  blade  always  parallel  to  the  sur 
faces.  Any  muscles  covering  it  ought  to  be  entirely  cut  away,  by  being 
divided  near  the  middle,  across  their  fibres,  the  two  ends  refiected  to  the 
side,  and  the  study  of  their  attachments  is  thus  more  easily  made. 
Remove  the  cellular  tissue  by  lifting  it  with  a  pair  of  forceps,  and  insert- 
ing the  edge  of  the  scalpel  in  the  angle  formed  by  the  cellular  tissue  and 
the  surface  of  the  muscle.  For  removing  fat,  glands,  kc,  scissors  may 
be  used  with  great  advantage.. 

DlSSECTIOX    OF    ALL    THE    MuSCLES    UPON    THE    SAME    SUBJECT. 

Place  the  subject  in  the  first  position,  and  commence  the  study  of  the 
muscles  of  the  inferior  abdominal  region.  Then  cut  ofi"  these  muscles, 
the  one  extremity  from  the  sternal  attachments,  the  other  from  the  pre- 
pubial  tendon  and  crural  arch.  The  cavity  of  the  abdomen  and  viscera 
will  thus  be  displayed  ;  and  the  latter  beii  g  removed,  the  student  should 
proceed  to  study  the  diaphragm,  internal  crural  region,  the  sublumbar 
region,  the  anterior  and  posterior  feporal  regions,  as  also  the  superficial 
muscles  of  the  inferior  cervical  and  pectoral  regions. 

Turn  the  animal  over,  and  place  it  in  the  second  position.  Dissect  the 
muscles  of  the  ears,  those  of  the  superior  cervical  region,  the  withers,  the 
costal  region,  the  spinal  region  of  the  back  and  the  loins,  and  the  region 
of  the  croup.  The  fore  limbs  may  be  partly  prepared  at  the  samo  time, 
one  being  removed  for  the  study  of  the  fore-arm  and  foot. 

Afterwards,  separate  one  hind  limb  by  sawing  the  femur  through  the 
middle,  and  then  proceed  to  the  dissection  of  the  muscles  of  the  leg  and 
hind  foot.  Then  by  means  of  another  cut  of  the  saw  carried  through  the 
middle  of  the  loins,  isolate  completely  the  pelvis,  to  make  a  dissection  of 
the  coccygeal  muscles  and  the  deep  muscles  of  the  internal  femoral 
region. 

The  animal  having  been  turned  upon  its  side  in  the  third  position, 
open  the  cavity  of  the  chest  and  saw  through  the  ribs  near  their  extre- 
mities, thus  forming  two  sections,  the  one  containing  the  triangularis 
sterni,  the  other  the  inferior  and  lateral  muscles  of  the  head  and  neck. 
The  subject  may  afterwards  serve  for  the  study  of  neai'ly  all  the  joints. 

Removal  of  the  Hoof. 
As  the  terminal  insertions  of  some  of  the  muscles  of  the  limks 
are  situated  in  the  interior  of  the  hoof,  it  is  absolutely  necessary,  iu 
order  to  see  them,  to  break  open  this  horny  case,  and  we  will  describe 
a  simple  method  of  performing  this  operation.  The  instruments 
necessary  for  breaking  open  the  hoof  are  a  scalpel,  a  chisel,  a  hammer, 
and   a   pair  of  strong   forceps.       The    limb   is   fixed    by    one    or   two 


568  APPENDIX. 

assistants  holding  it  in  a  vertical  position,  the  foot  resting  upon  a  table, 
stool,  or  solid  block  of  wood.  Push  in,  as  deeuly  as  possible,  the  blade 
of  the  scalpel  between  the  sensitive  and  the  hoi'ny  wall ;  move  it  about 
from  right  to  left,  and  make  it  follow  the  contour  of  the  latter.  By 
means  of  the  cliisel  and  the  hammer,  split  the  wall  into,  four  or  five 
fragments  by  a  convenient  number  of  vertical  incisions.  When  the 
wall  has  been  thi."  divided  into  several  segments,  detach  each  of  these, 
by  inserting  the  point  of  the  chisel  into  one  of  the  incisions,  and,  using 
this  instrument  as  a  lever,  throw  back  the  portion  of  horny  substance 
to  the  right  or  left.  The  flap  of  the  opposite  side  is  then  raised  and 
separated  from  the  subjacent  tissues.  Their  complete  detachment  will 
be  efiected  by  means  of  the  strong  forceps,  and  by  twisting  them  with 
considerable  force,  the  portion  of  the  wall  will  be  torn  from  the  sole. 
In  order  to  uncover  the  latter,  pass  the  blade  of  the  scalpel  between  the 
upper  face  of  the  horny  arch  and  the  sensitive  sole ;  push  the  point  of 
the  chisel  into  the  space  thus  opened,  raising  lightly  the  external  edge 
of  the  sole.  Then  seize  the  latter  with  the  forceps,  and  detach  it,  as 
well  as  the  frog,  by  a  v/rench,  giving  the  instrument  a  vigorous  move- 
ment backwards  and  forwards,  the  assistants  holding  the  limb  tightly 
and  with  a  force  opposed  to  that  of  the  operator. 


THE  ORGANS  OF  DIGESTION. 

The  Mouth. — The  whole  of  the  mouth  ought  to  be  examined  by  an 
antero-posterior  and  vertical  section  of  the  head. 

The  Palate. — Separate  the  head  from  the  trunk ;  then  saw  through 
the  ramus  of  the  inferior  maxillary  bone  above  the  angle  of  the  jaw  and 
the  ci'own  of  the  last  molar  tooth,  in  such  a  manner  as  to  pass  between 
the  velum  palati  on  the  omj  side,  the  base  of  the  tongue  on  the  other, 
and  leave  this  latter  organ  adherent  to  the  lower  jaw.  Separate  the 
lower  jaw  from  the  upper,  cutting  the  masseter  and  alveolo-labial 
muscles,  and  in  this  way  expose  the  palate  and  the  velum  palati,  upon 
which  it  will  then  be  possible  to  execute  easily  the  special  dissection 
necessary  for  their  study.  For  the  palate,  these  dissections  consist  in 
raising  the  mucous  membrane  which  conceals  the  deep  venous  plexus, 
and  in  the  partial  removal  of  the  latter  so  as  to  see  the  artery  and  the 
palatine  nerves. 

The  Tongue. — 1.  Make,  by  means  of  a  strong  saw  without  a  back,  an 
antero-posterior  and  vertical  section  of  the  head,  to  study  the  general 
disposition  of  the  tongue.  2.  Remove  from  another  head  the  lower  jaw, 
leaving  the  tongue  in  the  maxillary  space,  so  as  to  examine  the  external 
confjrmation  of  the  organ.       3.   Upon  another  head  intended  for  the 


APPENDIX.  569 

stady  of  the  muscles,  lay  bare  tnese  structures  in  the  following  manner: — 
Jlemove  entirely  the  masseter ;  detach  the  cheek  from  the  lower  jaw 
and  reflect  the  flap  upon  the  upper ;  saw  through  the  ramus  of  the  jaw 
transvercely,  immediately  behind,  and  then  before  the  line  of  the  molar 
teeth;  romove  and  dislocate  from  the  temporo-maxillary  articulation 
the  upper  fragment  of  the  bone,  destroying  the  capsular  ligament  and 
the  inserdlons  of  the  pterygoid  muscles ;  reverse  the  lower  fragment  so 
as  to  place  the  line  of  the  molar  teeth  below,  and  the  inferior  border 
of  the  bone  above,  in  the  bottom  of  the  intermaxillary  space ;  it  is 
sufficient,  in  performing  this  last  operation,  to  separate  the  buccal 
mucous  membrane  from  the  mylo-hyoid  muscle,  proceeding  from  above 
downwards.  The  dissection  thus  made  is  convenient  not  only  for  the 
study  of  the  muscles  of  the  tongue,  but  also  for  the  study  of  the  deep 
salivary  glands,  the  pharynx,  the  larynx,  the  guttural  pouches,  the 
perves  and  arteries  of  the  head,  &c.  It  is  always  well,  to  facilitate  this 
dissection,  to  keep  the  jaws  open  by  inserting  a  piece  of  wood  between 
the  incisor  teeth,  immediately  after  the  death  of  the  animal. 

The  Velum  Palati. — Study  the  velum  palati  :  1.  By  an  antero- 
posterior and  vertical  section  of  the  head.  2.  Make  the  dissection 
described  under  "The  Palate,"  and  dissect  off  the  mucous  and  glandular 
layer,  so  as  to  lay  bare  the  fibrous  membrane,  and  the  two  intrinsic 
muscles ;  the  extrinsic  muscles  ought  to  be  studied  with  those  of  the 
pharynx. 

The  Stomach. — In  order  to  study  the  organ  in  its  connections,  it  is 
sufficient  to  open  the  abdomen,  and  raise  the  intestinal  mass,  proceeding 
in  the  following  manner  : — The  animal  is  placed  in  the  first  position,  and 
slightly  inclined  to  the  left  side  ;  make  a  crucial  incision  upon  the  inferior 
abdominal  wall,  or  surround  all  this  wall  by  a  circular  incision,  taking 
care  not  to  wound  any  part  of  the  intestine ;  the  whole  mass  of  the 
viscera  is  then  drawn  out  of  the  abdominal  cavity  and  brought  upon  the 
table  which  supports  the  subject ,  do  not  allow  any  part  of  this  mass  to 
slip  down  upon  the  ground,  and  so  avoid  tearing  either  the  intestine  or 
the  parts  which  the  student  desir-^s  to  preserve  intact  in  the  abdominal 
cavity;  afterwards  cut  the  floating  colon,  at  the  point  of  its  union 
with  the  rectum,  and  the  duodenum,  where  it  passes  behind  the  great 
mesenteric  artery  ;  detach  the  base  of  the  caecum  from  the  sublumbar 
wall  by  the  rupture  of  the  cellular  tissue  which  connects  this  organ  with 
the  right  kidney  and  the  pancreas ;  destroy  the  same  cellular  union 
which  exists  between  the  pancreas  and  the  terminal  extremity  of  the 
fourth  part  of  the  colon  ;  separate  the  mesentery  along  with  the  vessels 
contained  between  its  folds;  the  intestinal  mass  is  thus  at  last  expelled 
^rom  the  abdominal  cavity,  and  a  couvenient  preparation  is  made,  not 


570  APPENDIX. 

only  of  the  stomach,  but  also  of  the  spleen,  liver,  pancreas,  kidneys^ 
ureters,  &c.  The  following  is  the  method  of  turning  the  stomach  inside 
out,  so  as  to  study  its  internal  surface,  and  to  dissect  its  muscular  coats  : 
— Cut  out  the  stomach,  with  about  three  inches  of  the  oesophagus,  and 
six  inches  of  the  duodenum,  and  then  proceed  to  wash  out  the  interior 
of  the  organ  in  the  following  manner, — introduce  a  quantity  of  water 
into  the  stomach  by  fixing  the  duodenum  to  the  stop-cock  of  a  cistern ; 
then  with  the  right  hand  relax -the  stomach,  holding  firmly  the  duo- 
denum with  the  left  hand  to  prevent  the  escape  of  the  liquid.  The 
alimentary  substances  contained  in  the  viscus  are  thus  mixed  v/ith  the 
water,  and  may  be  expelled  by  a  little  pressure  made  upon  the  stomach ; 
repeat  this  four  or  five  times,  thus  completely  washing  the  inner  surface 
of  the  organ.  To  invert  the  stomach,  making  the  external  surface  the 
internal,  introduce  through  the  duodenum  a  loop  of  iron-wire,  passing 
out  through  the  oesophagus ;  pass  through  the  loop  a  very  strong  waxed 
ligature,  and  then  tic  it  securely  round  the  oesophagus;  by  pulling  the 
iron- wire  passed  through  the  pylorus,  the  latter  will  be  sufficiently  dilated 
to  permit  the  passage  of  the  cardiac  end,  and  the  stomach  will  be  com- 
pletely inverted.  By  inflating  it,  the  stomach-may  be  easily  restored  to 
its  normal  form  and  disposition,  with  this  difference,  that  the  mucous 
surface  is  external,  and  the  serous  internal. 

The  Intestine. — The  study  of  the  intestine  must  be  made  on  a  special 
preparation ;  open  the  infei'ior  wall  of  the  abdomen  to  show  the  organs. 
But  as  the  mass  which  constitutes  it  is  heavy  and  difficult  to  move,  pro- 
ceed to  expel  the  contents  by  a  proceeding  analagous  to  that  described 
under  "  The  Stomach."  A  puncture  is  made  in  tte  csecum,  sufficient  to 
permit  the  escape  of  the  substances  accumulated  in  this  reservoir. 
Those  accumulated  in  the  colon  are  got  rid  of  by  an  incision  in  the  pelvic 
flexure,  those  in  the  rectum,  through  an  opening  made  in  the  floating 
colon  ;  the  small  intestine  is  cut  into  three  or  four  nearly  equal  parts. 
This  operation  having  been  completed,  inflate  the  intestines  so  as  to  show 
their  normal  size  ;  and  thus  the  general  disposition  of  the  intestinal  mass 
may  be  studied  with  the  greatest  ease  in  the  interior  of  the  abdomen. 
It  will  also  be  well  to  take  the  whole  .intestine  out  of  the  body  of  the 
animal,  and,  placing  it  upon  the  table,  isolate  the  different  parts,  study 
their  succession,  and  gain  a  complete  idea  of  their  form. 


THE  ORGANS  OF  CIRCULATION. 

Structure  of  the  Heart. — Before  proceeding  to  the  dissection  of 
the  muscular  fibres  of  the  heart,  it  is  indispensable  to  boil  this  viscus  in 
■water  for  half  or  three-quarters  of  an  hour. 


APPENDIX-.  571 

The  Heart. — Place  the  animal  in  the  second  position ;  remove  the 
sternal  ribs,  separating  them  from  their  cartilages ;  then  dislocate  the 
costo-vertebral  articulations.  This  dissection  permits  the  study  of  the 
situation  and  general  disposition  of  the  heart  and  of  the  pericardium. 
To  examine  with  ease  the  l-eciprocal  arrangement  of  these  two  organs,, 
remove  them  from  the  thoracic  cavity  by  detaching  the  sternal  insertion 
of  the  pericardium. 

Peeparation  op  Arteries. — The  preparation  of  arteries  consists  of 
two  successive  operations — 1.  Injection  ;  2.  Dissection. 

Injection  of  Arteries. — Injection  is  an  operation  consisting  of  the 
introduction  into  the  interior  of  the  vessels  of  a  solidifiable  substance,, 
intended  to  give  to  their  canals  the  volume  and  conformation  which  they 
present  during  life,  when  they  are  filled  with  blood.  Lard  mixed  with 
lamp-black  is  the  material  usually  employed.  Another  injection  some- 
times used  consists  of  gelatine,  mixed  with  a  certain  quantity  of  plaster 
of  Paris ;  but  this  is  little  used  in  the  French  school.  A  copper  or  brass 
syringe  and  a  nozzle,  fitted  with  a  stop-cock  upon  the  extremity  of  the 
syringe,  is  necessary  for  pouring  the  injection  into  the  arterial  vessels. 

The  method  of  making  a  general  injection  is  as  follows  : — The  animal 
having  been  laid  upon  a  table,  the  carotid  artery  is  laid  bare  by  meana 
of  an  incision  made  in  the  jugular  gutter.  The  vessel  is  opened  longi- 
tudinaUy.  A  ligature  is  applied  above  the  opening,  and  the  nozzle  is^ 
securely  fixed  in  the  artery,  upon  the  cardiac  side,  by  aid  of  a  second 
ligature.  The  injection,  prepared  beforehand,  is  drawn  into  the  syiinge. 
The  syringe  is  then  carefully  screwed  upon  the  nozzle,  and  the  piston  is 
pushed  steadily  onwards,  so  as  to  make  the  injection  pass  into  the 
arterial  canals. 

The  following  form  useful  injections  : — 


Lard,  or  Tallow, 
Oil  of  Turpentine, 
Colouring  Matter, 

Bees'-wax,  . 
Tallow,  . 
Colouring  Matter, 


9  parts. 
I     „ 


1  part. 

8     „. 
ad.  lib. 


Lamp-black,  Indigo,  and  Prussian  blue  may  be  used  for  the  veins; 
for  the  arteries,  as  vermillion  is  expensive,  Venetian  red  mixed  with  red 
lead  is  a  good  substitute. 

To  succeed  well  in  this  operation,  attend  carefully  to  the  following 
precautions : — 


572  APPENDIX. 

Inject  an  animal  which  has  been  killed  by  bleeding,  and  before  it 
is  cold,  and  wash  out  the  vessels  with  warm  water, 

2.  Heat  the  injection  to  a  degree  of  temperature  which  the  finger  can 
bear  without  pain.  If  it  is  colder,  the  lard  solidifies  too  soon  ;  if  it  is 
warmer,  it  may  shrivel  up  the  sigmoid  valves,  pass  into  the  left  ventricle, 
thence  into  the  auricle  and  pulmonary  veins,  an  accident  which  is  also 
sometimes  caused  by  pushing  the  piston  of  the  syringe  with  too  much  force. 

3.  Avoid  applying  too  much  force  to  the  piston. 

4.  Stop  the  injection  when  the  arteries  react,  by  their  elasticity,  upon 
the  piston,  so  as  to  drive  it  backwards. 

Instead  of  making  the  injection  into  the  carotid,  we  may  fix  a  long 
•curved  nozzle  into  the  aortic  trunk  itself,  after  having  made  an  opening 
into  the  left  side  of  the  chest,  at  the  level  of  the  heart,  by  cutting  away 
two  segments  of  the  ribs,  and  by  making  an  incision  into  the  pericardium 
over  the  left  ventricle,  so  as  to  introduce  the  nozzle  directly  into  the 
aorta.  This  proceeding  allows  the  injection  to  be  as  hot  as  possible,  and 
gives  sufficiently  good  results,  because  the  injection  then  penetrates,  if 
it  be  injected  under  favourable  conditions,  almost  into  the  capillary 
vessels  ;  and  ir  some  organs,  forces  the  injection  even  into  the  veins. 

But  whichever  method  is  followed,  there  are  certain  parts  which 
cannot  be  ioached  by  a  general  injection ;  thus  a  special  operation  must 
be  performed  to  force  the  injection  into  the  vessels  of  the  extremities. 
After  having  separated  them  from  the  trunk,  by  sawing  them  through 
above  the  knee  or  the  hock,  they  are  allowed  to  remain  for  two  hours  in 
a  bath  of  water,  kept  constantly  at  a  temperature  of  from  60  to  70 
degrees,  or  more,  and  then  they  are  very  easily  injected  through  the 
posterior  radial  artery  or  the  anterior  tibial,  or  through  any  of  the  other 
arteries  which  present  their  open  mouths  upon  the  section  of  the  limb. 
If  we  wish  to  make  partial  injections  of  other  parts  of  the  body,  it  may 
be  found  easier  not  to  separate  them  completely  from  the  trunk ;  but 
then  the  student  should  take  the  precaution  of  cutting  ofi"  or  tying  the 
vessels  which  establish  anastomotic  communications  between  the  arteries 
injected  and  those  which  he  does  not  wish  to  inject.  For  example,  if  he 
wishes  to  inject  the  arteries  of  the  head,  it  is  sufficient  to  inject  one  of 
the  two  common  carotids,  having  tied  the  other  in  the  middle  of  the 
neck,  and  the  two  vertebral -arteries  in  the  interstice  between  the  two 
portions  of  the  scalenus  muscle. 

To  inject  the  capillary  system,  recourse  is  had  to  other  substances,  and 
to  a  different  method.  The  following  may  be  used  :  varnish,  alcohol, 
essence  of  turpentine,  holding  in  suspension  very  fine  colouring  materials, 
gum  arable,  dissolved  and  coloured  by  any  soluble  colouring  matter,  and 
ijolours  ground  in  oil,  or  suspended  in  essence  of  turpentine. 


APPENDIX.  575 

Tfc  is  evident  that  the  pulmonary  artery  will  not  be  reached  by  the 
general  injection  already  described.  Inject  it  directly  by  passing  the 
injection  into  the  right  side  of  the  heart,  through  the  anterior  vena  cava, 
after  having  tied  the  posterior  vena  cava. 

Dissection  of  Arteries. — There  are  no  general  rules  to  be  given  for 
the  dissection  of  arteries. 

Injection  of  Veins. — It  will  make  the  study  and  dissection  of  the 
veins  easier,  to  fill  them  with  injection  ;  but  to  do  this,  a  difierent  pro- 
ceeding is  followed  from  that  described  for  arteries.  In  place  of  making 
the  injection  flow  from  the  trunks  towards  the  branches,  as  in  arteries, 
it  must  flow  Jrom  the  branches  to  the  trunks  in  the  case  of  the  veins, 
owing  to  the  presence  of  the  valves.  Four  injections  are  in  general 
sufficient  to  fill  the  whole  venous  system  in  a  satisfactory  manner  :  the 
first  is  poured  through  the  alveolar  vein  under  the  masseter  muscle:  the 
second  into  a  digital  vein  of  one  or  two  fore-limbs,  on  the  side  of  the 
foot,  after  having  destroyed  with  a  stylette  the  several  valves  which  are 
sometimes  found  near  the  point  of  union  of  the  roots  of  this  vein,  from 
the  cardiac  side  ;  the  third  into  a  posterior  digital  vein  ;  the  fourth  into 
an  intestinal  vein.  If  any  important  veins  require  tn  be  studied  after 
these  four  operations,  they  are  separately  injected. 

THE  LYMPHATIC  SYSTEM. 

The  lymphatic  plexuses  are  studied  after  having  being  injected  with 
mercury,  a  proceeding  which  may  be  very  briefly  described,  as  it  is 
seldom  done  by  those  for  whom  this  work  is  intended.  The  apparatus 
commonly  used  consists  of  a  tube  of  glass,  continued  by  a  flexible  tube, 
which  carries  at  its  lower  end  an  iron  stopcock  and  a  fine  cannula  made 
of  iron  or  glass.  To  use  this  apparatus,  fill  the  tube  with  mercury  and 
suspend  it ;  grasp  the  cannula  with  the  right  hand,  holding  it  parallel  to 
the  membrane  which  is  to  be  injected,  and  push  it  into  the  superficial 
layer  of  this  membrane.  The  extremity  of  the  cannula  is  thus  intro- 
duced into  the  middle  of  the  meshes  of  the  plexus,  and  of  course  wounds 
one  of  the  small  vessels  which  compose  it ;  then  turning  the  stopcock, 
permit  the  mercury  to  flow  into  the  vessels  through  the  jiuncture.  In 
this  way  they  may  be  perfectly  filled.  The  lymphatic  plexuses  being 
always  placed  above  sanguineous  ones,  always  take  the  precaution  of 
puncturing  the  membrane  as  superficially  as  possible,  because  if  the 
point  of  the  cannula  penetrate  too  deeply,  the  mercury  passes  into  the 
veins,  and  the  operation  is  a  failure. 

The  study  of  the  branches  and  trunks  of  the  lymphatics  may  also  be 
facilitated  by  inflating  them  from  their  origin  to  their  termination.     If 


574  APPENDIX. 

■well  done,  this  proceeding,  which  was  almost  exclusively  followed  by  the 
ancient  anatomists,  gives  very  satisfactory  results.  It  is  sxifficient  to 
demonstrate  the  texture  of  the  glands. 

The  Thoracic  Duct. — Ligature  the  jugular  and  brachial  veins  near 
their  termination,  as  also  the  anterior  vena  cava  about  its  middle ;  lay  bare 
the  thoracic  duct  by  cutting  the  right  ribs ;  open  it  near  the  pillars  of  the 
diaphragm,  and  pour  into  it  two  injections  of  lard,  the  one  before  and 
the  other  behind  the  incision.  The  first  injection  will  fill  the  duct  along 
•with  the  venous  reservoir,  which  is  intercepted  by  the  ligatures  applied 
to  the  vessels,  as  already  described ;  the  second,  since  it  is  directed  in 
the  opposite  direction  to  the  valves,  overcomes  the  resistance  ofiered  by 
them,  and  expands  the  canal  of  Pecquet  and  the  chief  branches  which 
end  in  it.  Another  method  is  as  follows : — One  of  the  branches  in  the 
abdominal  cavity  may  be  selected,  as,  for  example,  one  of  those  united 
to  the  colic  arteries,  near  their  origin,  and  the  thoracic  duct  completely 
injected  from  its  origin  to  its  termination.  But  this  operation  requires 
more  practical  dexterity  than  the  first,  in  order  to  reach  the  vessel  into 
which  the  nozzle  is  to  be  inserted  ;  and  it  is  not  at  all  easy  to  perform 
it  upon  fat  animals. 


THE  NERVOUS  SYSTEM. 

The  Braijst. — To  study  the  brain,  it  is  first  removed  from  the  cranial 
cavity.  This  is  done  by  two  operations.  The  first  consists  of  opening 
the  cranium  by  removing  its  vault,  using  a  saw,  a  chisel,  and  a  hammer, 
after  having  first  removed  all  the  parts  covering  it.  Then  open  the  dura 
mater  with  the  scissors,  and  expose  the  brain,  which  is  to  be  removed  by 
raising  its  posterior  extremity,  and  cutting  from  behind  forwards  all  the 
nerves  issuing  from  its  base,  with  the  pituitary  gland,  as  far  forwards  as 
the  end  of  the  olfactory  lobes.  This  operation  is  quickly  performed,  but 
it  does  not  permit  of  the  preservation  of  the  pituitary  gland,  which  is 
strongly  fixed  in  the  sella  turcica,  an  inconvenience  avoided  by  employ- 
ing the  following  method  of  opening  the  cranium  at  the  base.  After 
having  separated  the  head  from  the  trunk,  remove  the  inferior  maxilla, 
the  tongue,  the  hyoid  bone,  and  lay  bare  the  osseous  surface,  cutting 
away  all  the  soft  parts.  The  head  thus  prepared  is  held  by  an  assistant, 
the  cranial  vault  being  laid  upon  the  table  or  a  block  of  wood.  The 
operator  divides  the  zygomatic  arches  and  the  styloid  processes  of  the 
occipital ;  then  divides  in  succession  the  condyles  of  the  same  bone,  the 
basilar  process,  the  sphenoid,  the  palatines,  the  ethmoid  ;  and  returns  to 
the  lateral  parts,  which  he  cuts  through  successively  from  the  occipital  to 
the  ethmoid.     The  brain  having  been  thus  sufficiently  exposed,  the  dura. 


APPENDIX.  575 

•mater  is  set  free  as  in  the  first  operation,  and  raising  it  with  the  left 
hand,  the  adhesions  by  which  it  is  yet  fixed  to  the  vault  of  the  cranium, 
adhesions  chiefly  composed  of  the  veins  of  the  brain,  which  disgorge 
themselves  into  the  sinuses  of  the  dura  mater,  are  divided  by  the  scissors 
held  in  the  right  hand.  Break  down  the  adhesion  in  the  ethmoidal  fossa 
with  the  point  of  the  scalpel,  detach  the  olfactory  lobes,  and  the  mass  of 
the  brain  is  then  set  quite  free.  This  proceeding  is  an  operation  more 
difficult  than  the  first,  but  it  has  many  advantages,  preserving  intact  not 
only  the  pituitary  gland,  but  also  th^  ethmoidal  lobes ;  and  the  ganglia 
of  the  cranial  nerves  are  exposed  as  distinctly  as  the  nerves  themselves. 
Having  thus  described  the  means  of  removing  the  brain  from  its  osseous 
cavity,  it  is  enough  to  state  here  that  in  order  to  study  its  structure 
with  advantage,  it  will  be  well  to  have  two  brains,  hardened  by  soaking 
for  a  week  or  more  in  alcohol,  or  in  water  having  a  little  nitric  acid 
added  to  it  (1  to  20),  so  as  to  contract  the  nervous  substance,  and  make 
more  apparent  the  outline  of  the  cavities  of  the  brain. 


No.  II. 

ON  A  SUPERNUMERARY  OBLIQUE  MUSCLE  OF  THE 
EYEBALL. 

By  Thomas  Strangeways,  Professor  op  Veterinary 
Anatomy,  Edinburgh. 

{Journal  of  Anatomy  and  Fhynology,  second  series,  No.  II.,  May,  1868.) 

A  FEW  days  ago,  when  dissecting  the  muscles  of  the  eyeball  of  an  ass, 
in  the  dissecting  room  of  the  Veterinary  College,  I  was  somewhat 
astonished  at  finding  a  small  but  well-defined  muscle,  situated  between 
the  superior  and  inferior  oblique  muscles.  It  originated  by  a  delicate 
tendon  from  a  minute  depression,  in  the  superior  part  of  the  orbital 
plate  of  the  frontal  bone,  about  midway  between  the  origin  of  the 
inferior  oblique  and  the  loop  or  pulley  through  which  the  belly  of  the 
superior  oblique  passes.  The  tendon  of  origin  was  succeeded  by  a 
fusiform  fleshy  belly  of  about  three  lines  in  diameter,  and  about  an  inch 
in  length,  which  passed  obliquely  upwards  and  outwards  on  the  outer 
side  of  the  external  rectus.  The  belly,  embedded  in  a  quantity  of 
adipose  tissue,  terminated  in  a  thin,  flat  tendon,  which,  after  running 
nearly  parallel  for  a  short  distance  witii,  and  loosely  attached  by  cellular 


576  *  APPENDIX. 

tissue  to,  the  upper  part  of  the  belly  of  the  superior  oblique,  became 
blended  with  the  tendon  of  insertion  of  that  muscle  just  as  it  passed 
under  the  tendon  of  insertion  of  the  superior  rectus. 

As  there  are  some  slight  differences  between  the  arrangements  of  the 
oblique  muscles  of  the  eyeball  of  the  Equidae  and  those  of  Man,  it  may 
be  necessary  to  point  these  out,  so  as  to  prevent  any  misunderstandings 
as  to  the  position  of  this  small  obliqu-e  muscle. 

The  superior  oblique  muscle  in  the  horse  and  ass  is — \st,  Relatively 
longer  and  larger  than  in  man,  and  is  fleshy  for  some  distance  after  it 
has  passed  through  the  loop,  which  loop  is  situated  at  the  base  of  the 
orbital  process  of  the  frontal  bone  ;  2nd,  The  muscle,  after  passing 
through  the  loop,  extends  almost  directly  outwards  under  the  tendon 
of  the  superior  rectus,  to  gain  its  insertion  between  the  tendons  o£ 
insertion  of  the  superior  and  external  recti.  The  point  of  insertion  is 
thus  not  so  near  to  the  back  of  the  eyeball  as  in  man. 

The  inferior  oblique,  arising  from  the  lachrymal  fossa,  is  directed 
forwards  and  upwards,  its  belly  running  in  the  same  direction  as  the 
reflected  portion  of  the  supeiior  oblique,  and  becomes  finally  inserted 
between  the  tendons  of  insertion  of  the  external  and  inferior  recti,  much 
lower  down  and  also  farther  forwards  than  in  man. 

So  far  as  my  researches  have  gone,  this  small  muscle  has  not  hitherto 
been  described,  either  in  consequence  of  being  an  exceptional  occurrence 
in  this  animal,  or  of  having  been  overlooked.  There  can  be  no  doubt^ 
I  think,  of  its  being  an  accessory  or  check  muscle  of  the  superior 
oblique,  placed  there  for  the  purpose  of  preventing  the  belly  of  that 
muscle  becoming  fixed  in  the  loop  through  which  it  has  to  pass  at  such 
an  acute  angle,  in  the  lower  animals  more  especially. 

Unfortunately,  the  other  eyeball  had  been  removed  by  one  of  the 
students,  to  whom  the  subject  belonged,  before  I  had  commenced  my 
dissections  ;  but  still,  on  searching  within  the  orbit,  I  was  enabled  to 
find  part  of  the  belly  and  the  tendon  of  origin  of  a  similar  muscle,  which 
had  precisely  the  same  point  of  origin,  and  in  all  probability,  a  similar 
insertion.* 

*  (Since  the  abave  was  published,  Dr.  Johnston  has  dissected  the  muscle  in  both, 
eyes  of  two  subjects. — Ist  Edition.) 


APPENDIX.  577 


No.   III.    . 


ON  A  NON-STRIPED  MUSCLE  CONNECTED  WITH  THE 
OKBITAL  PERIOSTECJM  OF  MAN  AND  MAMMALS. 

By  Wm.  Turner,  M.B.  (Lond.),  F.R.S.E.,  Professor  op  Anatomy, 
University  of  Edinburgh. 

(Natural  History  Beview,  January,  1862.) 

"Whilst  engaged  in  making  a  dissection,  in  the  human  subject,  during 
the  winter  session  of  last  year,  of  the  superior  maxillary,  or  second 
division  of  the  fifth  cranial  nerve,  my  attention  was  attracted  to  a  pale- 
reddish,  soft  mass,  filling  up  the  narrow  chink  of  the  spheno-m axillary 
fissure,  and  extending,  from  the  sphenoidal  fissure  in  the  sphenoid  bone 
to  the  infra-orbital  canal  in  the  superior  maxillary  bone.  It  was 
evidently  connected  to  the  superior  (ocular)  aspect  of  the  periosteum 
of  the  orbit,  and  i'o  was  pierced  by  the  orbital  branch  of  the  cuperior 
maxillary  nerve,  from  which,  as  well  as  from  the  ascending  branches  of 
the  spheno-palatine  ganglion,  it  appeared  to  receive  its  supply  of  nerves. 
It  completely  chut  off  the  superior  maxillary  nerve,  with  its  infra-orbital 
continuation,  from  the  cavity  of  the  orbit 

Since  the  period  of  ma,king  the  above  observation,  I  have  availed 
myself  of  several  opportunities  of  examining  the  same  region  in  other 
subjects,  and  have  constantly  observed  appearances  of  a  nature  similar 
to  those  just  described  The  amount  of  the  reddish  mass,  and  the  depth 
of  its  tint,  varied  slightly  in  difierent  instances.  Frequently,  it  was  so 
pale  as  scarcely  to  attract  attention,  which  may  perhaps  be  the  reason 
why  it  has  so  long  been  neglected  by  anatomists.  When  carefully 
examined  with  the  naked  eye,  or,  still  better,  with  a  single  lens,  it  was 
seen  to  exhibit  a  fibrous  appearance.  A  small  portion  snipped  ofi'with 
scissors,  teazed  out  with  needles,  and  placed  on  the  stage  of  the  micro- 
scope,'under' a  quarter-inch  objective,  was  observed  to  be  composed  of 
pale,  flattened,  band-like  fibres,  having  a  faintly  granular  aspect,  and 
presenting  indications  of  elongated  nuclei  at  intervals.  From  these 
characters  I  had  little  doubt  that  the  structure  in  question  consisted  of 
the  non-striped  form  of  muscular  fibre. 

As  considerable  difficulty  is  always  experienced  in  obtaining  for 
examination  the  contents  of  the  human  orbit,  in  a  perfectly  fresh  con- 
dition, I,  in  the  next  instance,  proceeded  to  dissect  the  orbits  of  some 
of  the  more  readily  obtained  mammals,  with  a  view  of  ascertaining  if  a 

2  P 


578  APPENDIX. 

similar  structure  existed  in  them.  In  the  orbit  of  the  sheep  I  have 
most  satisfactorily  observed  appearances  which  have  fully  confirmed  the 
opinion  of  the  structure  already  expressed.  The  orbit  of  this  animal 
difiers  from  that  of  man  in  possessing  much  less  perfect  walls.  As  a 
consequence  of  this,  the  orbital  membrane,  or  periosteum,  is  a  structure 
of  much  importance,  for  it  stretches  across  the  floor  of  the  orbit  from 
its  outer  to  its  inner  wall,  extends  backwards  to  the  optic  foramen,  and 
completes  the  boundary  of  the  cavity  at  the  spot  where  the  bony  wall  is 
wanting. 

If  the  contents  of  the  orbit  be  carefully  removed,  and  the  orbital 
membrane  examined  from  above,  it  will  be  seen  to  be  a  well-defined 
structure  distinctly  fibrous,  and  in  many  places  having  an  almost 
tendinous-like  aspect.  Intimately  connected  with,  and  forming  an 
essential  part  of  it,  is  a  thin  layer  of  a  pale  reddish  substance,  which 
extends  across  the  greater  part  of  the  floor  of  the  orbit,  passing  back- 
wards to  the  optic  foramen  and  sphenoidal  fissure.  In  close  contact 
with  this  structure,  especially  at  the  posterior  part  of  the  orbit,  is  a 
well-marked  vascular  network,  suflSciently  injected  with  blood  to  be 
distinctly  visible.  This  vascular  plexus  constitutes  a  small  rete  mirabile, 
connected  with  the  ophthalmic  artery.  By  removing  a  small  portion  of 
the  reddish  mass,  teazing  it  out  with- needles  under  water,  and  examin- 
ing it  with  a  quarter-inch  objective,  it  may  be  seen  to  be  composed  for 
the  most  part  of  flat,  pale,  non-striped  fibres,  collected  together  in 
bundles,  having  a  faintly  granular  aspect,  and  exhibiting  decided  indica- 
tions of  nuclei  in  their  interior.  These  bundles  of  flat  fibres  are  mingled 
with  ordinary  fibrous  tissue,  both  white  and  yellow,  the  latter  becoming 
more  distinct  after  the  addition  of  acetic  acid.  The  pale,  non-striped 
fibres  have  all  the  characters  of  the  involuntary  muscular  fibre.  Being 
desirous,  however,  of  ascertaining  if  these  fibres  could  be  resolved  into 
their  constituent  fibre-cells,  I  adopted  the  plan  which  has  been  recom- 
mended by  Reichert,  and  macerated  a  portion  of  the  orbital  membrane 
for  forty--eight  hours  in  dilute  hydro-chloric  acid.  I  then  found  that,  by 
the  aid  of  a  very  slight  dissection,  the  fibres  readily  resolve  themselves 
into  the  elongated  fusiform  cells  of  which  they  were  composed.  In  no 
tissue  which  I  ever  examined,  consisting  of  the  non-striped  muscle, 
have  I  succeeded  in  obtaining  more  beautiful  and  more  perfect  specimens 
of  the  contractile  fibre-cell  than  in  this  muscle  of  the  orbital  membrane. 
The  fusiform  shape  of  the  cells,  their  size,  and  the  elongated  rod-like 
nucleus  in  the  centre  of  each  cell,  gave  to  the  texture  a  most  character- 
istic appearance,  I  may  also  mention,  that  when  the  orbital  muscle  in 
the  sheep  was  examined  without  the  addition  of  any  re-agent,  besides 
distilled  water,  a  number  of  elongated  rod-like  nuclei  were  always  met 


APPENDIX.  579 

-with,  lying  free  in  the  water  surrounding  the  preparation,  which  had 
evidently  been  loosened  and  detached  during  the  dissection  with  the 
needles.  These  nuclei  corresponded  in  their  characters  to  those  met 
with  in  the  interior  of  the  fibro-cells.  The  characters  which  I  have  now 
enumerated  render  the  muscular  nature  of  the  reddish  texture  connected 
with  the  orbital  membrane  sufficiently  clear. 

On  referring  to  the  authorities  who  have  written  on  the  structure  of 
-the  orbital  membrane,  I  find  that  the  following  opinions  have  been 
expressed  concerning  it : — 

Bmdz,  in  a  paper  *'  On  the  Orbital  Membrane  in  the  Domestic  Mam- 
mals," describes  it  as  distinctly  fibrous,  but  possessing  a  considerable 
■quantity  of  a  yellowish  tissue,  which  he  considers  to  be  elastic,  interpo- 
lated with  it.  He  regards  the  opinion,  which  had  been  previously 
advanced  by  Gurlt,  that  the  tissue  was  muscular,  to  be  erroneous. 
Stannius  states  that  in  those  animals,  in  which  the  bony  wall  of  the 
orbit  is  incomplete,  the  separation  between  the  orbital  cavity  and  the 
temporal  fossa  is  mostly  efiected  by  a  fibrous  membrane,  containing  also 
abundant  elastic  tissue.  He  states  that  Rudolphi  regarded  these  elastic 
fibres  to  be  muscular  in  bears,  and  that  Meckel  described  a  muscle  in  the 
orbital  membrane  of  Ornithorynchus.  Chauveau  speaks  of  the  fibrous 
membrane  which  completes  the  cavity  of  the  orbit  as  entirely  composed 
of  white  inextensile  fibres.  Gurlt  considers  it  to  be  a  strong  fibrous 
membrane,  with  yellow  elastic  fibres  interpolated.  E.  Miiller,  in  a  very 
brief  communication,  states  that  he  has  found  flat  muscular  fibres  in 
the  inferior  orbital  fissure  in  man,  and  corresponding  structures  con- 
nected to  the  membrana  orbitalis  of  mammalia. 

It  was  supposed  by  those  who  held  that  the  membrana  orbitalis  was  a 
highly  elastic  and  not  a  muscular  structure,  that  it  was  through  its 
elastic  recoil  that  the  eyeball  was  reprotruded  in  those  animals  which 
retracted  the  ball  through  the  contraction  of  a  retractor  muscle,  ff. 
Miiller,  again,  who  speaks  more  positively  than  any  who  have  preceded 
him,  not  only  of  the  existence  of  a  muscle,  but  also  of  the  kind  of  fibre 
of  which  it  is  composed,  considers  that  it  antagonises  those  muscles  which 
retract  the  eyeball  into  the  socket,  and  that  thus,  the  reprotrusion  of 
the  globe  is  produced,  not  by  a  mere  elastic  recoil  but  by  a  muscular 
contraction. 

If  this  hypothesis  be  correct,  an  arrangement  exists  in  this  locality, 
which  is  certainly  to  be  regarded  as  an  unusual  one — viz.,  an  involun- 
tary muscle  acting  as  a  direct  antagonist  to  a  voluntary  muscle. 
Whether  the  hypothesis  be  correct  or  not,  I  am  disposed  to  consider  that 
the  muscle  has  some  especial  relation  to  the  vascular  arrangements  in  the 
orbit.     Its  extension  backwards  to  the  foramina  through  which  the 


580  APPENDIX. 

orbital  vessels  proceed,  and  with  -wliich  it  is  in  immediate  relation,  and 
the  very  abundant  vascular  network  found  in  connection  with  it,  point, 
I  think,  to  some  special  relation  between  the  muscle  and  the  vessels,  a 
relation  which  is  not  at  all-  inconsistent  with  what  is  known  of  the 
function  of  non-striped  muscle  in  other  localities. 

****** 

Note. — Since  the  above  paper  was  in  type,  my  attention  has  been 
directed,  by  Professor  Huxley,  to  a  communication  by  H.  Miiller,  dated 
15th  Dec.  1860,  entitled  "  On  the  Influence  of  the  Sympathetic  upon 
some  Muscles,  and  on  the  extensive  occurrence  of  Unstriped  Muscles  in 
the  Skin  in  the  Mammalia." 

As  this  paper  throws  some  additional  light  upon  the  probable  action 
of  the  orbital  muscle,  I  append  a  short  abstract  of  it : — 

H.  Miiller,  after  referring  to  the  many  puzzling  questions  which  have 
arisen  respecting  the  function  of  the  sympathetic  nerve,  and  its  relations 
to  the  muscles  supplied  by  it,  proceeds  to  ask  two  questions — 

\st,  Whether,  and  which,  unstriped  muscles  are  supplied  by  other 
nerves  than  the  sympathetic  1 

2nd,  Whether,  and  which,  transversely-striped  muscles  are  under  the 
influence  of  the  sympathetic  ? 

In  answer  to  the  first,  the  action  of  the  oculo-motor  nerve  upon  the 
unstriped  fibres  of  the  iris  cannot  be  doubted  :  the  vagus  also  acts  upon 
unstriped  muscles,  and  the  experiments  of  Schiff  have  shown  that  the 
greater  part  of  the  vascular  nerves  are  not  connected  with  the  sympa- 
thetic. 

The  second  question  may  be  most  efi"ectively  answered  by  considering 
the  efiect  produced  upon  the  eyeball  by  division  or  irritation  of  the 
cervical  sympathetic.  Miiller,  for  this  purpose,  refers  to  the  experiments 
of  Bernard,  R.  Wagner,  and  Brown-Sequard ;  the  general  tendency  of 
which  is  to  show,  that  division  of  the  cervical  sympathetic  produces 
narrowing  of  the  palpebral  fissure,  retraction  of  the  bulb,  projection  of 
the  nictitating  membrane  and  narrowing  of  the  anterior  nares  and  the 
mouth.  Irritation  of  the  nerve  by  galvanisation,  on  the  other  hand, 
produces  increase  of  the  opening  of  the  lids,  projection  of  the  bulb  re- 
traction of  the  nictitating  membrane,  relaxation  of  several  facial  muscles. 
Respecting  the  causes  which  produced  these  changes  there  was  some 
diflference  of  opinion.  R.  Wagner  could  scarcely  conceive  that  any  force, 
save  the  contraction  of  the  two  obliqui,  could  produce  projection  of  the 
eyeball,  and  yet  he  asks,  "  How  could  these  transversely-striped  muscles 
receive  excito-motory  fibres  from  the  sympathetic]"  Brown-Sequard, 
again,  considered  that  retraction  of  the  bulb,  after  section  of  the  nerve, 
was  produced  by  the  active  contraction  of  the  retractor  and  recti,  and 


APPENDIX.  581 

"tLat  its  projection  by  subsequent  irritation  was  a  reposition.  Schiff 
Tegarded  the  projection  of  the  bulb  as  due  to  the  action  of  the  obliqui  : 
the  movements  of  the  lids  he  considered  to  be  passive,  and  due  to  those 
of  the  bulb. 

Remak  on  the  othef  hand,  believed  that  the  narrowing  of  the  palpe- 
bral fissure  was  due  to  a  relaxation  of  the  levator  palpebres  superioris, 
accompanied  by  a  spasmodic  contraction  of  the  orbicularis.  Moreover, 
he  conceived  that  the  sympathetic  acted  upon  the  voluntary  muscles  of 
the  lids  about  the  eye, 

Muller  considers  that  it  is  now  no  longer  necessary  to  discuss  the 
various  probabilities  respecting  the  influence  of  the  syn^pathetic  upon  the 
voluntary  muscles  of  the  eye,  as  a  complete  series  of  unstriped  musc'es 
have  now  been  observed,  which  will  serve  as  a  foundation  for  explaining 
i;he  movements  in  question. 

These  muscles  consist  of  three  divisions — 

1st,  In  the  orbital  cavity  cf  mammals,  a  membrane  (membrana 
orbitalis),  consisting  of  unstriped  muscles  with  elastic  tendons,  exists, 
which,  by  irritation  of  the  cervical  sympathetic,  projects  the  contents  of 
the  orbit,  especially  the  bulb,  forwards.  Retraction  is  produced  by  the 
transversely-striped  retractor.  In  man,  the  orbital  muscle  is  much 
reduced  in  size,  and  the  retractor  is  wanting,  so  that  a  distinct  projection 
of  the  bulb  does  not  follow  irritation  of  the  sympathetic,  as  Wagner  and 
H,  Muller  himself  have  observed, 

2nd,  The  projection  of  the  nictitating  membrane  in  mammals  is  mostly 
due  to  the  retractor  bulbi  under  the  influence  of  the  N".  abducens.  Its 
withdrawal  depends  on  some  unstriped  muscles  which  are  under  the 
influence  of  the  sympathetic.  In  hares,  however,  the  withdrawal  is  due 
to  a  transversely-striped  muscle,  which  is  nou  supplied  by  the  sympa- 
thetic but  by  the  oculo-motorius.  In  man,  the  lid  aiid  its  muscles  are 
rudimentary. 

3rd,  The  upper  and  lower  lid  possess  in  man,  and  in  very  many 
mammals,  unstriped  muscles,  which  have  the  power  cf  drawing  them 
back.  They  are  more  feeble  in  the  upper  than  the  lower  lid,  so  that 
by  irritation  of  the  sympathetic  the  latter  is  drawn  back  in  a  more 
marked  manner  than  the  former.  Narrowing  of  the  palpebral  fissure, 
after  section  of  the  cervical  sympathetic,  depends  upon  relaxation  of 
these  muscles.  Yet  recession  of  the  eyeball  may  depend  ■  upon  relaxa- 
tion of  the  orbital  muscle.  Miiller,  then,  concludes  that  the  movements 
occasioned  by  experimenting  on  the  cervical  sympathetic  are  not  such 
as  to  entitle  us  to  infer  an  inflnence  of  that  nerve  upon  voluntary 
striped  muscle.  He  also  considers  that  the  movements  about  the  nose 
and  mouth,  said  by  Bernard  to  be  produced  by  section  of  the  sympathetic, 


682  APPENDIX. 

if  they  do  take  place,  are  owing  to  the  presence  of  unstriped  cutaneous 
muscles. 

Muller  next  inquires  into  the  existence  of  unstriped  muscles  in  the 
skin  of  the  ear.  He  has  occasionally  found,  on  galvanising  the  cervical 
sympathetic  in  cats,  that  a  movement  of  the  hairs  growing  upon  the 
skin  at  the  entrance  of  the  concha  has  taken  place.  This  experiment 
has,  however,  frequently  failed  both  in  cats  and  other  animals.  A 
careful  examination  of  the  skin  of  the  part  did  not  give  any  indications 
of  unstriped  muscles,  but  very  distinct  muscles  were  seen  connected  to 
the  hair  follicles.  He  considers  these  experiments  of  interest,  as  they 
appear  to  indicate  whence  the  muscles  of  the  hair  follicles  receive  their 
nerves.  Owing  to  the  movement  of  the  hairs  being  limited  to  a  very 
small  locality,  during  the  irritation  of  the  sympathetic,  one  must  suppose 
that  only  a  very  small  part  of  the  unstriped  muscular  apparatus  of  the 
skin  of  the  cat  can  be  regulated  by  the  cervical  sympathetic. 


IISTDEX 


ABDOMEN:  300. 

regions  of,  300. 
Abdominal  rings,  203. 

tunic,  '200. 
Abducens  nerve,  497. 
Accessory  organs  ot  digesJion.|U^.^_  ^^^^ 

in  Kuminants,  373. 
Acervulus  cerebri,  484. 
Acetaliuluiu,  h7. 
Adipose  tissue,  123. 
^stliesiology,  525. 

comparative,  552. 
Air  cells,  339. 
Albinos  in  Rodentia,  553. 
Alimentary  canal,  275. 
AUantois,  557. 
Alula,  554.    . 
Alveoli  canine,  58,  63 

incisor,  58,  63. 
molar,  57. 63. 
Amnion,  557.    . 
Amphiarthrosis,  127. 
Amptiioxus,  4. 
Ampnllse,  530. 
Analogy,  6.. 
Anapopbysis,  112. 
Anaioiny.  animal,  1. 

comparative,  1. 
descrii)live,  6.  ,      .  , 

distinguished  from  physiology,  2. 
divisions  of,  6. 
minute,  2. 
morbid.  2. 
practical,  2. 
special,  1. 
surgical,  2. 
transcendental,  l. 
veterinary,  2. 
Andersch's  ganglion,  499. 
Angiology,  387. 

comparative,  458. 
Annular  cartilage,  .'^26. 

ligaments,  124. 
Anterior  aorta.  418. 

in  Omnivora,  461. 
in  Ruminants,  459. 
nares,  42. 
vena  cava,  442. 
Anus,  311. 

Aorta  anterior,  418. 
common,  40]. 
in  aves,  463. 

posterior,  402.  . 

Aponeurotic  tendons  and  fascia,  159. 
Apophysis.  16. 
Appendages  of  the  eye,  5J». 
Appendicular  joints,  f^-^^^^.^^^^^  ^,3. 
in  Omnivora,  153. 
in  Ruminantia,  152. 


Appendicular  skeleton,  65._ 

of  Dog,  112. 
of  Hog.  108. 
of  Rodent,  115. 
of  Ruminant,  103. 
Appendix  I,,  565. 
II.,  575. 
III.,  577. 
Aaueduct,  14. 

of  Sylvius,  483. 
of  Fallopius-  51. 
of  vestibule,  ^l.  531. 
Aqueous  humour,  536. 
Arachnoid  membrane,  4C9. 
Arbor  vitte,  476. 

uterinus,  361. 
Arch,  crural,  202. 
hfemal,  23. 
neural,  21. 
palatine,  38,  60. 
pectoral,  66. 
pelvic,  83. 
radio-ulnar,  70. 
tibial,  93. 
zygomatic,  40. 
Arcuate  ligaments,  209. 
Arnold's  ganglion,  516. 
Arrangement  of  fascite,  252. 
Arteries,  3>i8. 

structure  of,  399. 

augulaiof  eye,  427. 

anterior  abdominal,  420. 

antei  iiir  aorta,  418. 

anterior  auricular,  430. 

atiterioi-  cerebellar,  486. 

anterior  cerebral,  487. 

anterior  choroid,  488. 

anteiior  communicating,  488. 

auieriiir  deeu  temporal,  432. 

anterior  radial,  422. 

anterior  tibial,  416. 

arteria  .'entrails  retinae.  432,  536. 

arteria  humeralis  profunda,  422. 

arteria  pedis  perforans,  416. 

arteria  profunda  femoris,  414. 

arteria  superflcialis  femoris,  414. 

asternal,  420. 

basilar,  486. 

brachial.  418. 

brachio-cephalic,  418,  463. 

broncho-oesophageal,  404. 

buccal,  433. 

cardiac,  40i. 

carotid,  424. 

carpal  arch,  inferior,  423. 

carpal  arch,  .superior,  422. 

centralis  retina;,  4J2. 

cephalic,  424. 

cerebral,  486. 

cerebro-spinal.  426,  486. 

ciliary.  4'ti. 


584 


Arteries,  circle  of  Willis.  487. 

circulu.s  arteriosus,  418. 

circumflex,  418. 

circumflex,  ilii.  412. 

coccygeal,  4ii. 

coeliac  axis,  404. 

colic,  407. 

common  aorta,  401. 

common  carotid.  418,  424. 

coraco-radial,  422. 

coronary,  401. 

cubital,  or  ulnar,  422. 

digital,  417, 424. 

dorsal,  419. 

dorsal  nasal,  427. 

dorsal  of  penis,  413. 

duodenal,  406. 

epigastric.  412. 

ext  -rnal  carotid.  427. 

external  iliac,  4il. 

external  thoracic,  421. 

external  plantar,  415. 

external  pudic,  413. 

femoral,  412. 

femoro-popliteal,  414. 

gastric,  404. 

gastro-epiploic,  405,  406. 

glosso-facial,  427. 

gluteal,  411. 

great  meningeal,  431. 

great  mesenteric,  407. 

great  matatarsal,  416. 

hEemorrhoidal,  407. 

hepatic,  405. 

humeral,  422. 

humeralis  profunda,  422. 

hypogastric,  559. 

iliaeo-femoral,  411. 

ilio-lumbar,  411. 

ilio-esecal,  411. 

inferior  cervical.  420. 

inferior  circumflex,  418. 

inferior  dental.  431. 

inferior  labial  or  coronary,  429. 

intercostal,  403- 

internal  carotid,  426,  -IST. 

internal  iliac.  409. 

internal  maxillary,  431. 

internal  plantar,  415. 

internal  pudic,  410. 

internal  thoracic,  420. 

interosseous  of  fore-arm,  423. 

interosseous  palmars.  424. 

interosseous  plantars,  415. 

ischiatic,  4ii. 

lachrymal,  432. 

lateral  laminal,  417. 

large  metacarpal,  424. 

lateral  nasal,  427,  432. 

lateral  sacral,  4ii. 

lesser  mesenteric,  407. 

lingual,  428. 

lumbar,  403. 

mammary,  413. 

masseter,  "430. 

mastoid.  426. 

maxillo- muscular,  429. 

meningeal,  432. 

middle  cerebral.  488. 

middle  sacral,  404. 

middle  spinal,  426.  486. 

musculo  occipital.  426. 

nutrient  humeral,  422. 

nutrient  radial,  423. 

nutrient  scapular,  421. 

obturator.  411. 

occipital,  425. 

of  the  bulb,  410. 

of  the  cord,  409. 

of  fore-limb  Carnivora,  462. 

of  the  Frog,  417. 

onhthalmic,  432. 


Arteries,  orbital,  433. 
palatine,  433. 
palato-labial,  433. 
l)crforating  pedal,  416. 
peroneal,  416. 
perpendicular,  417. 
pharyngeal  or  ascending  pharyn- 
geal, 428. 
phrenic,  403. 
plantar,  415 
plantar  ungual,  418, 
popliteal,  414. 
posterior  abdominal,  412. 
posterior  aorta,  402. 
posterior  auricular,  430. 
posterior  cerebellar,  4.86. 
posterior  cerebral.  486. 
posterioi  circumflex,  421. 
posterior  communicating,  487, 
posterior  deep  temporal,  431. 
posterior  masseter.  430. 
posterior  radial,  423. 
posterior  tibial,  415. 
prehumeral,  422. 
preseapulai»,  421. 
preplantar  ungual,  417. 
prepubian,  412. 
prevertebral,  426. 
profunda  femoris,  414. 
pterygoid-fasciculus,  431. 
pterygoidean,  430. 
pulinonary,  400. 
pyloric,  406. 
radio  palmar.  423. 
ramus  anastomoticus,  426< 
ranine,  428. 
recurrent  radial,  423. 
renal,  408. 
sapheuic.  414. 
scapulo-humeral,  421. 
sesamoidean  arch.  416. 
small  metacarpal,  423. 
small  muscular,  414. 
small  testicular,  409. 
solar,  418. 
spermatic,  408. 
spheno-spinal,  431. 
spheno-palatine,  433. 
spiral,  422. 
splenic.  405. 
staphyline,  433. 
subcutaneous  abdominal,  418, 
subcostal,  419 
sublingual,  428. 
submaxillary,  427, 
subscapular,  421- 
subzygomatic,  430. 
superficial  temporal,  430. 
superflcialus  femoris,  414. 
superior  cervical.  420. 
superior  dental,  433. 
superior  labial  or  coronary,  489. 
supraorbital,  432. 
thyroid,  425. 
thyro-laryngeal,  425. 
transverse,  417. 
transver.se  facial,  430. 
tympanic,  431, 
ulnar.  422. 
umbilical,  409,  559. 
uterine.  409. 
utero-ovarian,  409. 
vaginal,  4ii. 
vertebral,  420. 
vesico- prostatic,  410. 
Arthrology,  120. 

comparative,  151. 
Articular  cartilage,  121. 

depressions,  15. 

eminences,  14. 

facet.  15. 

head,  14. 


INDEX. 


585 


Articulations,  atlo-axoid,  131. 
chondro-eostal,  133. 
coccypeal  132. 
commor  vertebral,  129. 
costo- sterna)  133. 
costovertebral  132. 
distal  intarohalangeal,  142. 
femoro-pe'vi"  145, 
femoro-tibial,  146. 
humero-radial  136. 
ischio-pubic  (symphysis),  145. 
metacarpal  140. 
metacarpo-phalangeal,  140. 
occipito-atloid   131. 
of  appendicular  skeleton,  136. 
of  axial  skeleton,  129. 
of  axial    skeleton   in  Eumi- 

nantia,  151. 
of  carpus,  137. 
of  hyoid  series.  135. 
of  pectoral  limb.  136. 
of  pelvic  limb,  143. 

of  skull.  134. 

pectoral  limb  in  Ruminantia, 

152. 
pelvic  limb  in  Euminantia, 

152. 

proximal  interphalangeal,l42. 
radio-ulnar,  137. 
sacro-iliac,  143. 
sacro-lumbar.  132. 
scapulohumeral.  136. 
special  vertebral,  131. 
sternal,  134. 
tarsal,  149. 

temporo-maxillary,  134. 
tibiofibular,  148. 
thoracic,  132. 
Astragalus,  93. 
Atlas,  26. 

Atlo-axoid  articulation,  131. 
,     ^  space,  28. 

tudltory  bulla.  51. 

ossicles,  527. 
ossicles  in  Aves,  554. 
Aves,  6. 

skeleton  of,  115. 
*iixial  joints  in  Carnivora,  153. 
Omnivora,  163. 
,    ,  ,  „  Ruminantia.  151. 

-Vxial  Skeleton,  21. 

articulations  of,  129. 
Carnivora,  109. 
Omnivora,  105. 
Rodentia,  114. 
Ruminantia,  98. 
Axis,  27. 

BaBBS,  664. 

Bars  of  the  hoof,  645. 

of  the  mouth,  63. 
Base  of  the  brain,  477. 
easement  membrane,  272. 
Bastard  wing,  554. 
Bellini,  tubes  of,  343. 
Bicipital  groove,  69. 
Bilateral  symmetry,  19. 
Bile,  317. 
Biology,  1. 
Birds,  characteristics  of,  6. 

eye  in,  554. 

muscles,  269. 

pectoral  arch,  117. 

sketeton  in,  116. 
Bladder,  344. 
Blastoderm,  666. 
Blood,  387. 

in  Aves,  463. 
Blood-Vascular  System,  387, 
Bones,  canaliouli  of,  10. 

cannon^  77. 

cardiac.  1O6. 


Bones,  classes  of,  12. 

coffin,  81. 

contents  of,  12. 

covering  of,  11, 

cranial.  45. 

cubo-cuceiform,  104. 

cuneiform  of  tarsus.  95,  96,  97. 

density  of,  8. 

development  of,  16. 

diploe  of,  11. 

ethmoid,  64. 

facial,  54, 

flat,  13. 

frontal,  48. 

hyoid,  64. 

inferior  maxillary,  62. 

innominate.  84. 

irregular,  13. 

lachrymal,  59. 

lacunae  of,  9. 

large  metacarpal,  77. 

large  pastern,  80. 

large  sesamoid.  80. 

long,  12. 

lymphatics  in,  12. 

malar,  68. 

malleolar,  104. 

metacarpal,  77. 

metatarsal,  97. 

minute  structure  of,  9. 

nasal,  54. 

navicular.  83. 

neck  of,  15. 

nutrient  foramina  of,  12. 

occipital,  45. 

of  carpus.  72, 

of  digit,  79. 

of  hind  limb,  88. 

of  penis  in  c  arnivora.  114, 

of  Ruminant  skull,  98. 

of  tarsus,  93. 

palatine,  59. 
parietal,  47. 
petrosal,  50. 
pisiform,  77. 
pneumatic,  119. 
premaxillary,  67. 
Pterygoid,  60. 
quadrate,  117.  , 
quadrato-jugal,  117. 
small  pastern,  81. 
small  sesamoid,  83. 
sphenoid,  52. 
splint.  78. 
squamosal,  49. 
stifle.  91. 
structure  of,  7. 
superior  maxillary,  66. 
surfaces  of,  14. 
temporal,  49. 
turbinated,  61. 
unciform,  76. 
vessels  of,  12. 
Vomer,  61. 
Wormian,  48. 
Bowman,  capsules  of,  342. 
Brachial  arteries,  branches  of,  4i9. 
Brain,  473. 

arterial  circulation  of,  486. 
in  Aves,  524. 
in  Carnivora,  523. 
in  Omnivora,  623. 
in  Rodentia.  624. 
in  Ruminants,  522. 
meninges  of.  469. 
removal  of,  674. 
sand,  484. 

venous  circulation  of,  488. 
Branches  of  jugular  vein,  447. 
Broad  ligaments  of  uterus,  323. 
ligament  of  bladder,  346. 

of  coffln-joint,  143. 


586 


INDEX. 


Broad  ligament  of  digrit.  Hi. 
'  of  liyer,  314. 

Bronchial  tubes,  335. 
Bronchi,  335. 
Bursae  mucosae,  125. 
synovial,  125. 

Cxcvii.  307. 
Calamus,  564. 

scriptorius,  476. 
Calcaneo-cuboid  ligament,  150. 
Calcaneum,  94. 
Calvarium,  37- 
^anal.  14. 

alimentary,  275. 
Haversian,  9. 
,  inguinal,  203. 

lachrymal,  56,  59. 
neural,  3,  21. 
of  Gartner,  376. 
of  Petit,  536. 
€analiculi  of  bone,  10. 
Cancellated  tissue^  10. 
Cannon  bone,  77. 
€anthi,  538. 
Capillaries,  400. 
Capsular  ligaments,  124. 
Capsule  of  the  lens,  537. 
Cardiac  bones,  105,  468. 
Cariniform  cartilage,  36. 
Carnivora,  bone  of  penis,  114. 

characteristics  of,  6. 
clavicle  in,  113. 
joints  in,  153. 
skeleton  in.  109. 
tapetum  lucidum  in,  653. 
Carotid  artery,  424. 

in  Carnivora,  462. 
in  Omnivora.  461. 
Carpal  cuneiform  bone,  74. 
joint,  137 
bones,  72. 
Cartilage,  120. 

articular,  121. 
cariniform,  36. 
cellular,  122. 
ensiform,  86. 
flbro-,  121. 
glenoid,  142. 
hyaline,  121. 
lateral,  549. 
of  ear,  626. 
semilunar,  147. 
tarsal,  539. 
temporary,  15. 
xiphoid,  36. 
Carunculae  myrtiformes,  362. 
lachrymales,  540. 
"Cat  hairs,"  544. 
Cauda  equina.  471. 
Cavernous  sinuses,  489. 
Cavicomia,  4. 
Cavities,  cotyloid,  i5. 
glenoid.  15. 
in  the  skull,  42. 
Cells,  air.  339. 
giant,  12. 
osteoblastic,  17. 
Cellular  cartilage,  122. 
Centrum  ovale  majus  and  minus,  479, 
C«re.  555. 
Cerebellum,  475. 
Cerebral  commissures,  483. 
convolutions,  477. 
lobes.  477. 
sulci,  477. 
Cerebrospinal  system,  468. 
Cerebrum,  476. 
Cereminous  glands,  526. 
Cervical  fascia,  253. 
nerves,  503. 
vertebrae,  general  features.  23. 


Cervical  vertebrae,  special,  26, 

the  two  last,  28. 
Chambers  of  the  eye,  ."136. 
Characteristics  of  Aves,  5. 

of  Carnivora,  5. 
of  Equidae.  4. 
of  Omnivora.  5. 
of  Rodentia,  5- 
of  Ruminantia,  6. 
of  vertebrata,  3. 
Chataignes,"543. 
Check  ligament,  227,  228. 
Cheeks,  276. 

Chondro-costal  articulation,  133. 
Chorion.  657. 
Choroid  coat,  534. 

plexus,  482. 
Chyle,  45). 
Ciliary  muscle,  534. 

processes,  635. 
zone,  536. 
Ciliated  epithelium,  271. 
Circle  of  Willis,  487. 
Circulation,  397. 

in  foetus,  559, 
in  lower  animals,  463. 
Classes  of  bones,  12, 
of  joints,  126. 
Classification  of  muscles,  161. 
Clavicle,  66. 

in  Carnivora.  113. 
^,  ^     ,  in  Aves,  117. 
Cleft  of  Frog,  547. 
Clitoris,  362. 
Cloaca,  384. 

Coccygeal  articulations,  132. 
nerves,  485. 
vertebrae,  32. 
Coccyx,  32. 
Cochlea,  530. 
Coeliac  axis  in  Carnivora,  461. 

in  Ruminants,  468, 
Cofnn  bone,  81. 
jo-'nt,  142. 
Colon,  floating,  3lo. 

great  308. 
Column  vertebral,  21. 
Columnar  epithelium,  271. 
Commissures  of  the  cord,  472. 
of  Frog  548. 
optic,  478.  492. 
Common  aorta,  401. 

carpal  ligaments,  139. 
tarsal  ligaments,  149. 
vertebral  articulations,  129. 
vertebral  ligaments,  129. 
Compact  tissue,  9. 
Comparative  Anatomy,  1. 

.SIsthesiology— Aves,  554. 
Carnivora,  563. 
Omnivora,  552. 
Rodentia,  653. 
Ruminantia,  652. 
Angiology— Aves.  462. 

Carnivora,  461. 
lower  animals,  463. 
Omnivora,  460. 
Rodentia,  462. 
Ruminantia,  463. 
Anthrology— Carnivora,  163. 
Omnivora,  153. 
Ruminantia.  15t 
Myology— Aves,  269. 

Carnivora,  265. 
Omnivora,  263, 
Rodentia,  268. 
Ruminantia,  260. 
Neurology— Aves,  524. 

Carnivora,  623. 
Omnivora,  623. 
Rodentia,  524. 
Buminantia,  ;>22. 


INDEX. 


587 


Comparative  Osteology— Aves,  115. 

Carnivora  109. 
Omnivora,  105. 
Rodentia,  lu. 
Buminantia.  98. 
Splanchnology— A ves,  381. 
Carnivora,  380. 
Omnivora.  377. 
Rodentia,  383. 
Ruminantla,  365. 
conclia,  525. 
Oonchal  cartilage.  526. 
Conduit,  lachrymal,  56. 

parieto-temporal,  42,  50. 
Vidian,  62,  60. 
Condyles,  14. 
Cofluent,  parieto-temporal,  489. 

subsphenoidal,  489. 
Conjunctiva,  639. 
Connective  tissue,  122. 
Contents  of  bone,  12. 
Conus  medullaris.  471. 
Coracoid  apophysis,  66. 
Corlum,  542. 
Cornea,  533. 
Corona  glandis,  ^5. 

tubulorum,  306. 
Coronary  arteries,  40l. 

band.  551. 
Coronoid  process,  63, 
Corpora,  genlculata,  483. 
nigra,  635. 
Quadrigemina,  484. 
Corpus  albicans,  47S. 
callosum,  479. 
flmbrlatum,  481. 
Highmorianum,  349. 
luteum,  368. 
striatum,  481. 
Costo-sternal  artriculation,  133. 
Costo-vertebral  articulation,  133. 
Cotyloid  cavity,  15, 
notch,  87. 
Covering  of  Bone,  11. 
"  Cow-kicks,"  152. 
Cowi)er's  glands,  362. 
Cranial  bones,  45. 

nerves.  490. 
Cranium.  37,  42. 
Crest,  14. 

Cribriform  plates,  64. 
Crista  galli  process,  54. 
Crura  cerebri,  477. 

of  diaphragm,  203. 
penist  364. 
Crural  aponeurosis,  202. 

arch,  202. 
Crust,  546. 
Ocusta  petrosa,  290. 
Ccystalrine  lens,  637. 
Cubo-cuaeiform  bone,  104. 
Csboid  bone.  95. 
Cuneiform  bones,  95,  96,  97. 

bone  of  carpus,  74, 
bones  of  hog,  109. 
Cuticle.  541. 
Cutigeral  groove,  645. 

Deep  fascia,  252. 

veins  of  arm,  445. 
Deltoid  ridge,  68. 
Density  of  bone,  8. 
Dental  formulffi,  294. 
Dentata,  27. 
Dentine,  289. 
Dentition,  288.  ; 

in  Carnivora,  380. 

in  Hog,  377. 

In  Rodentia,  383. 

In  Ruminant,  366. 
Depressions,  articular,  is. 

non-articular,  14. 


Dermis,  542. 
Descriptive  anatomy,  6. 
Development  of  bone.  15. 
of  foetus,  561. 
of  teeth,  295. 
of  ulna,  72, 104. 
Diaphragm,  208. 
Diaphysis.  16. 
Diarthrosis,  127. 
Diastema,  38,  57,  63. 
Digit,  bones  of,  79. 
Digestive  system.  275. 

in  Aves,  384. 

in  Carnivora,  380. 

in  Omnivora,  377. 

in  Bodentia,  383. 

in  Buminant.  365. 
Diploa  of  bone,  11. 
Dissection,  general  directions  for,  565. 

of  articulations  and  ligamentaL 

565. 

of  lymphatic  system.  573. 
of  muscles,  666. 
of  nervous  system,  674. 
of  organs  of  digestion,  563. 
of  organs  of  circulation,  57o. 
Distal,  20. 

phalanx,  81. 
Division  of  skeleton,  20. 
of  skull,  37. 
of  sphenoid  bone,  52. 
of  anatomy,  l. 
Domesticated  Aves,  5. 

Mammals,  4. 
Dorsal  nerves,  505. 

vertebrsB.  28. 
Dorso-lumbar  fascia,  253. 
Duct,  hepatic,  3i7. 

of  Bartholini,  366. 
of  Nuckius,  380. 
of  Bivinus,  287. 
of  Steno,  286. 
of  Warton,  287. 
of  Wlrsung,  318. 
thoracic,  451. 
Ductus  ad  nasum,  541. 

arteriosus,  40l,  559. 
choledochus,  317. 
cochlearis,  531. 
communis,  317. 
lactiferus,  364. 
lymphaticus  dexter  468. 
pancreatlcus  minor,  3l9i. 
reuniens,  531. 
Duodenum,  304. 

Eae,  525. 

Eiaculatory  ducts,  351. 
Elbov?  joint,  136. 
Embryo,  656. 
Embryogenlc  tissue,  556. 
Embryology,  2, 556. 
Eminence  of  Vater,  317. 
Eminences,  anticular,  14. 

ilio-pectineal,  86. 

non-articular,  14. 
Enamel,  290. 

Encephalic  circulation,  485. 
Encephalon,  473.     ' 
Endocardium.  396. 
Endolymph,  531. 
Endoskeleton,  17. 
Endosteum,  il. 
Endothelium,  271. 
Ensiform  cartilage.  36. 
Epidermis,  541. 
Epididymis,  350. 
Epiphysis,  16. 
Epithelium.  270. 

Eauidae.  characteristics  of  the.  4. 
Erectile  tissue,  354. 
Ethmoid  bone,  54. 


588 


Ethmoidal  sinus,  45. 
Eustachian  tubes,  528. 

openings  for,  51. 
Exoskeleton.  17. 
External  ear,  625. 

jugular  vein.  Rodents,  462. 
Eye,  532. 

appendages  of,  538. 
in  Aves,  554. 

Fabella:  in  Carnivora,  113. 
Rodentia,  115. 
Facet,  articular,  15. 
Facial  bones,  54- 
Fallopian  tubes,  358. 
False  vertebrae,  23. 
Falx  cerebelli,  470. 

cerebri,  470. 
Fascia,  159. 

arrangement  of,  252. 

crural,  202. 

deep,  252. 

deep  abdominal,  253. 

inguinal,  347. 

of  the  anterior  limb,  254. 

of  external  oblique,  202. 

of  the  head,  253. 

of  the  posterior  limb,  255. 

of  the  trunk,  253. 

perineal,  356. 
■  plantar,  228. 
Pat,  123. 
Feathers,  anatomy  of.  554. 

classiflcation  of,  554. 
Felidse,  retractor  ligament  of  claw,  267. 
Female  genital  organs,  357. 

in  Ruminants,  376. 
Female  pelvis,  88. 
Femur,  89. 

Ferrein,  tubes  of,  343. 
Fetlock  joint,  140. 
Fibro-cartilage,  yellow.  122. 

varieties  of,  121. 
Fibula,  93. 
Fifth  ventricle,  481. 
Fissures,  15. 

of  Sylvius,  477. 
of  the  cord,  472. 
Flat  bones.  13. 
Foetus,  556. 

circulation  in,  659. 

Foot.  544. 

circulation  of,  417. 439. 
soft  structures  of,  549. 
Foramen,  i*. 

aortic  (hiatus),  209. 

cibcum,  474. 

condyloid,  46. 

dental,  57. 

dextrum,  209. 

Eustachian,  51. 

external  auditory  (meatus),  51. 

incisivum,  58. 

inferior  dental,  63. 

infra-orbital.  56. 

internal  auditory  (meatus),  50. 

internal  orbital,  52. 

lacerum  basis  cranii,  40. 

lacerum  orbitale,  53. 

lachrymal  (conduit).  56. 

magnum,  45. 

mental,  63. 

obturator,  87. 

of  Fallopius  (aqueduct),  61. 

of  Monro,  481. 

of  the  vestibule  faqueduct),  61. 

optic,  62. 

palatine,  56,  60. 

parieto-temporal  (co^iduit),  42, 
60. 

patheticum.  93. 

plantar,  82. 


ForeLmen,  preplantar,  82. 

pterygoid,  30,  52. 
rotundum,  53. 
sinistrum,  209. 
spheno-palatine,  57,  60. 
stylo-mastoid,  51. 
styloid,  51. 

subsphenoidal,  39, 52. 
supra-orbital,  48. 
Vidian  (canal),  52.  60. 
Fore-arm,  bones  of.  70. 
Fore-limb,  bones  of,  66. 
Forms  of  uterus  in  mammalia,  384. 
Fornix,  480. 
Fossa,  14. 

cavernous,  53. 
lachrymal,  59. 
nasal,  44. 

navicularis,  353,  362. 
orbital,  41. 
sphenoidal,  45. 
supracondyloid,  89. 
temporal,  41. 
Fourth  ventricle,  476. 
Frog,  547. 

band,  548. 
sensitive,  550. 
Frontal  bone,  48. 
sinus,  44. 
Fundus  acetabuli,  87. 
Funicular  ligaments,  124. 
tendons,  159. 

Ganglia,  Andersch's,  499. 
Gasserian.  493. 
genicular,  498, 
guttural,  516. 
inferior  cervical,  618. 
jugular,  500. 
lenticular,  515. 
Meckel's,  516. 
of  spinal  nerves.  503. 
otic,  516. 
petrosal,  499. 
semilunar,  520. 
superior  cervical,  516. 
sympathetic,  615. 
Gartner,  canals  of,  376. 
General  view  of  the  skull,  37. 
Generative  system,  346. 
Genicular  ganglion,  498. 
Genital  system  in  early  foetal  life,  368. 

in  Ruminant,  37.^ 
Genito-urinary  organs  in  Aves,  386. 
^.       .    ^  .,  Rodents,  383v 

Giant's  Cells.  12. 
Gizzard,  384. 
Glands,  274. 

Brunner's,  306- 
buccal,  277. 
ceruminous.  626. 
Cowper's,  352. 
ductless,  274. 
gastric,  303. 
lachrymal,  540. 
liver,  312. 
lymphatic.  460. 
mammary,  363. 
minor  salivary,  287. 
molar,  277. 
mucous,  272. 
Nabothian,  361. 
of  Harder,  640. 
of  intestines,  306. 
of  pancreas,  318. 
of  skin,  642. 
parotid,  285. 
prostate,  351. 
salivary,  285. 
solitary,  306. 
spleen,  319. 
submaxillary.  287. 


INDEX. 


589 


Glands,  sublingual.  287. 

thyroid  and  thymus,  335. 

uropygeal,  555. 
Glans  penis.  354. 
Glandular  epithelium,  271. 
Glaserian  Assure,  51. 
Glenoid  cartilage,  142. 

cavity,  15. 
Globe  of  the  eye,  582. 
Glosso- facial  artery  in  Carnivora,  462. 
Graafian  vesicle,  358. 
Great  cerebral  commissure,  479. 
Grey  matter  of  the  cord,  472. 
Groove,  bicipital,  69. 

palatine,  56. 

staphyline,  60. 
Gums,  277. 
Guttural  ganglion,  516.     ' 

pouches,  531. 
Gyrus  fornicatus,  479. 

"Hmmat,  system,  3. 

Hair,  423, 

Harderian  glands,  540. 

Haversian  canals,  9. 

Haw.  539. 

Head,  articular,  14. 

Heart,  388. 

in  Aves,  462. 

in  Carnivora,  461. 

in  lower  animals,  463. 

in  Rodents,  462. 

in  Ruminants,  458. 

muscular  fibres  of,  395. 

structure  of,  394. 
Heels,  545. 
Helicotrema,  530. 
Henle,  tubes  of,  343. 
Hermaphrodite,  363. 
Hiatus,  14. 

aortieus,  209. 
maxillary.  57. 
of  Winslow,  322. 
optic,  43,  53. 

orbital,  5-2. 
Hind  limb,  bones  of,  88. 
Hip  joint,  145. 
Hippocampus,  481. 
Hippotomy.  3. 
Histology,  2. 
Hock  joint,  149. 
Homology  and  Analogy,  6. 
Hoof,  544.    . 

in  Ruminantia,  552. 
Horn  tissue,  548. 
Horns  in  Ruminantia,  552. 
Horny  laminae,  545. 
Humerus,  68. 
Humours  of  the  eye,  536. 
Hyaline  cartilage,  varieties  of,  121. 
Hyaloid  membrane,  537. 
Hymen,  362. 
Hyoid  series  of  bones,  64. 

articulations  of,  135. 

Ileum,  305. 

Iliac  arteries  in  Carnivora,  461. 

Ilium,  84. 

Incisura  sphenoidalis.  48. 

Incus,  527. 

Inferior  cervical  ganglion,  518- 

maxilla,  62. 

pyramids.  474. 
Infundibu]um,478. 
Ingluvies,  384. 
Inguinal  canal,  203. 
Injection  of  arteries,  571. 

of  lymphatics,  573. 
of  veins,  573. 
Interdental  space,  38. 57,  $3. 
Intermediate  fasciculi,  475. 
Internal  ear,  529. 


Internal  iliac  artery  of  Omnivora,  461. 

maxillary   artery  in  Carnivorei, 

462. 

Interpeduncular  space,  478. 
Intervertebral  discs,  129. 
Intestines,  304. 

glands  of,  306, 

in  Aves,  384. 

in  Carnivora,  381. 

in  Omnivora,  378. 

in  Ruminants,  371. 

large,  3C7. 

small,  304. 
Introducti6n,  1.  . 

Invertebrata  and  vertebrata  compared,  3, 
Iris,  535. 

Irregular  bones,  13. 
Ischium,  86. 
Island  of  Reil,  477. 
Isthmus  faucium,  278. 
Iter  ad  infundibulum,  483. 

e  tertio  ad  quartum  ventriculum,  483. 

Jejunum,  305. 
Joint  oil,  125. 
Jugular  confluent,  446. 

ganglion,  500, 

gutter,  446. 

vein,  446. 

Keratogenous  membrane,  55() 
Keratophyllous  tissue,  545. 
Kidneys,  340. 

Labyrinth,  529. 

membranous,  531. 
Lachrymal  apparatus,  540. 
bone.  59. 
conduit,  56. 
duct,  541.    . 
fossa,  59. 
gland,  540. 
Lactiferous  duct,  364. 

sinuses,  364. 
Lacunae  of  bone,  9, 
Lamina  spiralis,  530. 
Lamprey,  4. 
Laneelet,  4. 
Larynx,  327. 

cartilages  of,  327. 
intrinsic  muscles  of,  331. 
ligaments  of,  329. 
extrinsic  muscles  of,  331. 
ventricles  of,  330. 
Lateral  cartilages.  549. 
sinuses,  489. 
ventricles,  480. 

cornua  of,  480. 
Lamina  cinerea,  479. 
cribrosa,  533. 
Left  auricle,  392. 

ventricle,  393. 
Lenticular  ganglion,  515. 
Levator  palatl  muscle,  279. 
Ligaments,  124. 

arcuate,  209. 

broad,  I4i. 

calcaneo-cuboid,  150. 

capsular,  124. 

cervical,  {ligamentum  tiucficeX 

130. 
check,  227,  228. 
common  of  carpus,  139. 
common  of  tarsus,  149. 
common  vertebral,  129. 
crico-trachealis,  329. 
funicular,  124. 
inferior  sesamoidean,  141. 
laryngeal,  329. 
obturator,  145. 
of  bladder,  345. 
of  liver.  314. 


590 


INDEX. 


liigamects  of  uterus,  360. 

of  tympanum,  528. 
of  vulva,  3«3. 
Poupart's,  202. 
pubio-femoral,  146. 
retractor  of  claw  in  cats,  267. 
round,  146. 
sacro-sciatic,  144. 
special  carpal,  137. 
special  tarsal,  150. 
special  vertebral,  130. 
superior  sesamoidean,  141. 
suspensory,  I4i. 
transverse  odontoid,  153. 
V,  X,  and  Y.  141". 
Limb,  bones  of  pectoral,  66, 

of  pelvic,  88. 
Unea  alba,  201. 

semilunaris,  200. 
Lips,  276. 
Liquor  amnii,  557. 

Contunnii,  530. 
Morgagni,  537. 
Scarpae,  531. 
Liver,  312. 

in  Omnivora,  379. 
ligaments  of,  314. 
structure  of,  314. 
Locomotion,  organs  of,  6, 
Locus  niger,  478. 

perforans,  anticus   and  posticus, 

478. 

Long  bones,  12. 
Longitudinal  sinuses,  489. 
Low  forms  of  vertebrata,  4. 
Lumbar  nerves,  505. 

vertebrae,  30. 
Lunar  bone,  74. 
Lungs,  337. 
Lymph,  451. 

corpuscles,  451. 
Lymphatic  system,  449. 
vessels,  449. 
Lymphatics,  brachial,  457, 

deep  inguinal,  463. 

bronchial  glands,  455. 

glands,  450. 

guttural,  457. 

iliac,  453. 

in  bone  tissue,  12. 

in  ruminants,  460- 

of  abdominal  viscera,  454. 

of  anterior  region,  456. 

of  caecum,  454. 

of  diaphragm,  456, 

of  large  colon,  454. 

of  liver,  455. 

of  posterior  region,  452. 

of  rectum  and  floating  colon, 
454. 

of  spleen,  455. 

of  stomach,  455. 

of  thoracic  viscera,  455. 

of  thoracic  walls,  456. 

popliteal,  453. 

precrural,  453. 

prepectoral,  456. 

prescapular,  457. 

sublumbar,  452. 

submaxillary,  457. 

superficial  inguinal.  453. 

valves  of,  450. 

vein,  458. 
Lyra,  481. 

Malab  Bone,  5R. 

Male  gejiital  organs.  346. 

in  Ruminant,  375. 
Malleolar  bone,  104. 
Malleus,  527. 
Malphigian  bodies,  341. 

corpuscles,  321. 


Mammalia,  4. 

Mammals,  domesticated,  4, 
Mammary  glands,  263. 
Mammillary  eminence,  478. 
processes,  115. 
Mandible,  62. 
Manubrium,  103. 
Marrow,  12. 
Mastoid  ridge,  46. 
Maxillary  hiatus,  57. 
Maxilla  inferior,  62, 
pre-,  57. 
superior,  56. 
Maxillary  nerve,  inferior,  495. 
superior,  494, 
rami,  38. 
sinus,  44. 
space,  38, 62. 
Meatus,  14. 

external  auditory,  51. 
internal  auditory-  50. 
nasal,  62. 
urinarius,  354. 
Meckel's  ganglion,  5i6. 
Median  phalanx,  81. 
Mediastinum,  337. 

testis,  349. 
Medulla  oblongata,  473. 
Medullary  cone,  471. 
Meibomian  glands,  539. 
Membranes,  basement,  272. 
basilar,  531. 
fusca.  534. 
mucous,  272. 
nictitans,  539. 
of  Reifesner,  531. 
osteogenic,  17. 
pupiharis,  535. 
serous,  273. 
synovial,  124. 
tympanic.  526. 
Meninges  of  the  brain.  469. 
cord,  468. 
Meniscus,  134. 147. 
Mesenteries,  321. 
Metacarpal  articulation,  140. 
bone,  large,  77. 
bones,  small,  78. 
Metacarpus,  77. 
Metapophyses,  115. 
Metatarsal  bones,  97. 
Metatarsus,  97. 
Middle  ear.  526. 
Minute  anatomy,  2. 

structure  of  bone,  9. 
Monro,  foramen  of,  481. 
Morbid  anatomy,  2. 
Morphology,  2. 
Motion  in  joints,  128. 
Motores  oculorum,  492. 
Mouth,  276. 

bars  of,  63. 
Mucous  membranes,  272. 
Muscles,  abdominal  region,  200. 
abdncens,  177. 
abductor  brevis  pollicis,  267 
abductor  minimi  digiti.  267, 
accelerator  urinae,  355. 
acromio-humeralis,  266. 
adductor  brevis,  238. 
adductor  Indicis,  267. 
adductor  longus,  239. 
adductor  magnus,  239. 
adductor  minimi  digiti,  267. 
anconeus,  221. 
antea-spinatus,  213. 
anterior  femoral  region,  241. 
anterior  maxillary  group,  16\ 
anterior  tibial  group.  245. 
antibrachial  extensor  group.  2*2. 
antibrachial  flexor  group,  226. 
aryteno-pharyngeus,  298. 


INDEX. 


591 


Muscles,  arytenoideus,  333. 

attollens  anticus,  175. 
attollens  maximus,  174. 
attollens  posticus,  176. 
auricular  group  (extrinsic),  174. 
auricular  group  (intrinsic),  177. 
biceps  rotator  tibialis,  244. 
brachial  group  (anterior),  217. 
brachial  group  (posterior),  219. 
buccinator,  163. 
caput  magnum,  220. 
caput  medium,  220. 
caput  parvum,  221. 
cervical  region,  178. 
coccygeal  region,  210. 
complexus  major,  186. 
complexus  minor,  187. 
compressor  coccygis,  211. 
constrictores  vulvae,  363. 
coraco-humeralis.  218- 
costal  region,  190. 
cremaster,  355. 

crico-arytenoideus  lateralis.  332. 
crico-arytenoideus  posticus,  332. 
crico-pharyngeus,  298. 
crico-thyroideus,  332. 
crural  group,  242. 
crurerus,  243. 
curvatoi-  coccygis,  211. 


depressor  coccygis,  210. 

depressor  labii  inferioris,  167. 

depressor  labii  superioris,  166. 

diaphragm.  208. 

digastricus,  170. 

dilatator  naris  inferioris,  166. 

dilatator  naris  lateralis,  165. 

dilatator  naris  superioris,  166. 

dilatator  naris  trausvorsalis,  166. 

dorso-lumbar  region,  198. 

erector  clitoridis,a63. 

erector  coccygis,  210. 

erector  penis.  356. 

extensor  communis  digitorum, 

262. 
extensor  metacarpi  magnus,  222. 
extensor  metacarpi  obliquus,  223. 
extensor  pedis,  223,  247. 
extensor  pedis  brevis,  252. 
extensor  poUicis  et  indicis.  266. 
extensor  proprius  externus,  262. 
extensor  proprius  internus,  262. 
extensor  suffraginis.  224. 
femoral  abductor  group,  239. 
femoral  adductor  group,  236. 
flexor  brachii,  21?. 
flexor  brevis  pollicis.  267. 
flexor  metacarpi  externus,  225. 
flexor  metacarpi  internus,  226. 
flexor  metacarpi  medius,  226. 
flexor  metatarsi,  245. 
flexor  minimi  digiti,  267. 
flexor  pedis  accessorius,  251, 
flexor  pedis  perforans,  228,  250. 
flexor  pedis  perforatus,  227, 249. 
frontalis,  261. 
gastrocnemius,  248. 
gemelli  (gemini),  235. 
genio-hyo-glossus,  283. 
genio-hyoideus,  171. 
gluteal  region,  231. 
gluteus  externus,  232. 
gluteus  internus,  233. 
gluteus  maximus.  232. 
gracilis,  237. 

humeralis  obliquus,  218. 
hyo-epiglottideus,  331. 
hyo-glossus  brevis,  282. 
hyo-glossus  longus.  282. 
hyo-glossus  parvus,  282. 
byo-pharyngeus,  298. 

hyo-thyroideus,  331. 


Muscles,  hyoidean  group,  170. 
hyoideus  magnus.  171. 
hyoideus  parvus.  172. 
hyoideus  transversus.  172. 
iliacus,  207. 
in  birds,  269. 

inferior  cervical  group,  178. 
inferior  oblique  of  eye,  538. 
intercostales.  194. 
interossei  (hog),  264. 
interossei  metacarpei,  230. 
intertransversales  lumborum, 

200. 
intertransversalis  colli.  189. 
ischio-femoralis.  244, 
keratopharyngeus,  297. 
lachrymalis,  173. 
laryngeal,  331. 
lateral  cervical  group,  183. 
lateralis  sterni,  197. 
latissimua  dorsi,  191. 
levator  alas,  269. 
levator  ani,  312. 
levator  humeri,  183. 
levator  labii  inferioris,  167. 
levator  labii  superioris  alaeque 

nasi,  164. 
levator  palati,  279. 
levator  palpebrae  superioris  ex» 

ternus,  173. 
levator  palpebrae  superioris  in- 
ternus. 174. 
levatores  costarum,  193, 
lingual,  281. 
lingualis,  283. 
longissimus  dorsi,  198. 
longus  colli,  182. 
lumbricales,  231. 
masseter,  168. 
mastoido-auricularis.  177. 
metacarpal  region,  230. 
metatarsal  region,  252. 
mylo-hyoideus,  170. 
nasalis  longus,  164. 
obliquus  abdominis  externus. 

201. 
obliquus  abdominis  internus,  209, 
obliquus  capitis  anticus,  188. 
obliquus  capitis  posticus,  188. 
obturator  externus.  234. 
obturator  internus,  235. 
of  dog's  paw,  266. 
of  eye,  537. 

of  female  genital  system.  363, 
of  head,  162. 
of  larynx.  331. 
of  limbs.  211. 

of  male  genital  organs,  355. 

of  pectoral  limb,  212. 

of  pelvic  limb,  231. 

of  pharynx.  297. 

of  Phillips,  224. 

of  soft  palate.  278. 

of  Thiernesse,  224. 

of  tongue,  281. 

of  trunk,  178. 

of  tympanum.  528. 

opponens.  267. 

orbicularis  oris,  164. 

orbicularis  palpebrarum,  173. 

palatoglossus,  280,  283. 

palato-staphylinus,  280. 

palmares,  267. 

palmaris  brevis,  267. 

palpebral  group,  173. 

panniculus  carnosus,  161. 

pectiiieous.  237. 

pectoral  region  and  group,  194. 

pertoralis  anticus,  196. 

peetoralis  magnus,  196. 

pectoralis  parvus,  197. 

peetoralis  transversus.  195. 


692 


Muscles,  peroneus,  2il. 

peroneus  longus  lateralis,  263. 
pharyngeal,  297. 
pharjngo-glossus,  283. 
pharyngo-staphylinu.s,  279,  297. 
plantaris,  249. 
popliteous.  251. 
postea-spinatus,  2U. 
postea-spinatus  minor,  2U. 
posterior  femoral  region.  244. 
posterior  maxillary  group,  167. 
posterior  tibial  group.  248. 
pronator  auadratus,  266. 
pronator  teres,  266. 
psoas  magnus.  205. 
psoas  parvus,  206. 
pterygo-pharyngeus,  297. 
pterygoideus  externus,  169. 
pterygoideus  intern  us,  169. 
pyriformis,  235. 
auadratus  lumborum,  207. 
Quadriceps  cruralis,  242. 
radialis  aecessorius,  230. 
recti  oculi,  537. 
rectus  abdominis,  204. 
rectus  capitis  anticus  major,  180. 
rectus  capitis  anticus  minor,  181. 
rectus  capitis  lateralis,  181. 
rectus  capitis  posticus  major,  187. 
rectus  capitis  posticus  minor,  187. 
rectus  femorls,  242. 
rectus  parvus,  234. 
retractor  ani,  312. 
retractor  oculi,  537. 
retractor  penis,  356. 
retrahens  externus,  176. 
retrahens  internus,  177. 
retrahens  medius,  176. 
rhomboideus  brevis,  190. 
rhomboideus  longus,  184. 
sarforius,  236. 
scalenus,  181. 

scapular  group  (pxternal),  212. 
scapular  group  (internal),  215, 
scapulo-humeralis  posticus 

(grele).  216.. 
scapulo-ulnaris,  219. 
scuto-auricularis  externus,  178. 
scuto-auricularis  internus,  178. 
semispinalis  dorsi  et  lumborum, 

199. 
serratus  magnus,  185, 192. 
sphincter  ani,  311. 
spinalis  colli,  189. 
spinalis  dorsi,  199. 
splenius,  185. 
sternal  group,  197. 
sterno-maxillaris,  179. 
sterno-suboccipitalis,  261. 
sterno-thyro-hyoideus.  179. 
stylo-hyoideus,  172. 
stylo-maxillaris,  168. 
subcutaneous  region,  161. 
subscapularis,  215. 
subscapulo-hyoideus,  180. 
sublumbar  region,  205. 
superfleialis  costarum,  192. 
superior  obliQue  of  eye,  538. 
supinator  brevis,  266. 
supinator  longus,  266. 
temporalis,  168. 
tensor  fasciae  latae,  241. 
tensor  palati,  278. 
teres  externus,  212. 
teres  internus  (major),  215. 
thyro-arytenoideus,  333. 
thyro-pharyngeus,  298. 
tibial  region,  245. 
tibialis  anticus,  263. 
tibialis  posticus,  268. 
trachelo-altoideus,  261. 
'  trachelo-mastoideus,  186. 


Muscles,  transversalis  abdominis,  205. 

transversalis  costarum,  193, 

trapezius  cervicalis,  184. 

trapezius  dorsalis,  190. 

triangularis  sterni,  198. 

triceps  abductor  femoris,  240. 

triceps  adductor  femoris,  238. 

triceps  cruralis,  242. 

triceps  extensor  brachii.  219. 

ulnaris  accessorius.  229. 

vastus  externus,  243. 

vastus  internus,  243. 

Wilson's,  356. 

zygomaticus,  163.    ' 
Muscular  attachments,  table  of,  256. 
classification,  160. 
nomenclature,  160. 
tissue,  155. 
Myelon,  47i. 
Myology,  155. 

comparative,  260. 

NaBES,  ANTEBIOR.  42. 

posterior,  39. 
Nasal  bone,  54. 

chambers.  335. 
duct,  541. 
fOSSiB,  44. 

meati ,  62. 
Natatores,  6. 
Nates,  484. 
Navicular  bone,  83. 
Neck  of  a  bone,  14. 
Nerve  cells,  466. 
Nerves,  467. 

abducens,  497. 

anterior  auricular,  498. 

anterior  palatine,  494. 

anterior  scapular,  508. 

anterior  tibial,  514. 

auditory,  499. 

auricular  plexus,  503. 

axillary,  508 

brachial  plexis,  508. 

bronchial  plexus,  501. 

buccal,  496. 

cardiac,  518. 

carotid  ple.xus,  518. 

Cauda  eauina,  506. 

cavernous  plexus,  517. 

cephalic  portion  of  sympathetic, 
515. 

cervical,  503. 

cervical  portion  of  sympathetic, 
516. 

chorda  tympani,  498. 

circulatory  depressor,  in  Babbit. 

524. 

classification  of,  468,  490. 

cochlear,  499. 

coccygeal,  50". 

cranial,  490. 

crural,  512. 

cubital,  5Q9. 

deep  cervical  plexus,  504, 

dental,  494,  496. 

digital,  511,514. 

dorsal.  505. 

external  popliteal,  514. 

external  saphenic,  514. 

facial,  497. 

facial  branches  of  fifth,  494. 

gastric  plexus,  520. 

glosso-  pharyngeal,  499. 

gluteal  aute-ior,  512. 

gluteal  posterior,  512. 

great  sciatic,  513. 

great  splanchnic,  520. 

gustatory,  496. 

guttural  plexus,  516. 

tiEemorrhoidal.  507. 

hepatic  plexus,  520. 


INDEX. 


593 


Servos,  hypogastric  plexus.  507,  521. 
hypoglossal,  502. 
illiaco-muscular.  512. 
ilio  muscular,  512. 
in  Aves,  524. 
in  Carnivora,  523. 
in  the  Hog,  523. 
in  Ruminants,  522. 
inferior  dental,  496. 
inferior  maxillary,  495. 
inguinal,  506. 
intercostal,  505. 
intermediate  cord  of  cervical 

ganglia,  518- 
internal  metacarpal,  5lo. 
internal  pudic,  507. 
internal  saphenic.  512. 
ischio-muscular,  512. 
Jacobson's,  500. 
lachrymal.  494. 
lesser  splanchnic,  521. 
lingual,  496. 
lumbar,  505. 
lumbar  portion  of  sympathetic, 

521. 
lumbo-aortic  plexus,  520. 
lumbo-sacral  plexus,  5ii. 
masseter,  495. 
median,  509. 
mental,  496. 
mesenteric  plexus,  520. 
metacarpal,  5ii. 
metatarsal.  514. 
middle  auricular,  499. 
motores  oculorum,  492. 
musculo-cutaneous  (fore-limb), 

510. 

musculo-cutaneous  (hind-limb), 

514. 

mylo-hyoidean,  496. 

nasal,  494. 

obturator,  512. 

olfactory,  491. 

ophthalmic,  493. 

optic,  491. 

orbital,  494. 

origin  and  termination  of,  467. 

parvagum,500. 

pathetic,  492. 

pharyngeal  plexus,  518. 

phrenic,  507. 

pneumogastric.  500. 

portio  dura,  497. 

portio  mollis,  499. 

posterior  auricular,  499. 

posterior  crural,  514. 

posterior  mesenteric  plexus,  521. 

pterygoid,  496. 

radial,  508. 

recurrent  laryngeal,  501. 

renal  plexus,  520. 

sacral,  506. 

saoral  portion  of  sympathetic, .. 

521. 

solar  plexus,  520. 
spermatic  plexus,  521, 
spheno-palatine,  494. 
spinal,  502. 
spinal  ascessory,  502. 
sp'enic  plexus,  520. 
staphyline,  494. 
subscapular,  508. 
subzygomat'c,  496. 
superficial  cervical  plexus,  504. 
superficial  petrosal,  498. 
superior  dental,  494. 
superior  laryngeal,  .500. 
superior  maxillary,  494. 
supraorbital.  493. 
suprarenal  plexus,  520. 
sympathetic  system,  615. 
temporo-facial,  499. 


Nerves,  thoracic,  508. 

thoracic  portion  of  sympthetio, 

519. 
tibial,  513. 

tracheal  plexus,  519, 
trifacial,  492. 
ulnar.  509. 
vestibular,  499. 
Vidian,  498. 
Wrisberg's,  498. 
Nervous  tissue,  466. 
Neural  canal,  3. 
Neuroglia,  473. 
Neurology,  465. 

comparative,  522. 
Nomenclature,  muscular,  160. 
Non-articular  depressions,  14. 

eminences.  14. 
Non-stnated  muscular  tissue,  157 
Nostrils,  323. 
Notch,  14. 

carotid,  53. 
cotyloid,  87. 
inferior  maxillary,  53. 
Notochord,  4,  557. 

Obtubatob  foramen.  87. 

ligaments,  145. 
Occipital  bone,  45. 

bone,  segments  of,  46. 
sinuses,  489. 
Ocular  sheath,  541. 
Odontoid  ligament,  transverse.  153, 

process,  27. 
(Esophagus,  298. 
Olecranon  process,  72, 
Olfactory  bulbs,  479. 
Olfactory  lobes  in  carnivora,  523, 

nerves,  491. 
Olivary  bodies,  474. 
Omenta,  322. 
Omnivora,  characteristics  of,  3. 

skin  in,  552. 
Opthalmic  nerve,  493. 
Optic  hiatus,  43,  53. 
lobes,  484. 
nerves,  491. 
thalami,  482, 
tracts,  478. 
Orbital  fossa,  41. 

hiatus,  52. 
Organs  of  locomotion,  6. 
Oscalcis,  94. 
coronas,  81. 
hyoides,  64. 
innominatum,  84. 
magnum,  76. 
orbiculare,  527. 
pedis,  81. 
suffraginus,  80. 
triquetrum.  48. 
uteri,  361. 
Osseous  tissue,  9. 
Ossiflc  centres,  15. 

tentorium,  42,  47. 
Ossification,  15, 
Osteoblasts,  11. 
Osteology,  7. 

comparative,  98. 
Osteogenic  membrane,  17. 
Ostium  internum,  361. 
uterinum,  3tii. 
Otic  ganglion,  616. 
Oto-conise,  531. 
Ovary,  357. 
Oviduct,  358,  386. 
Ovum,  358. 

after  fecundation,  o8fi. 

Pacinian  bodies,  467. 
Palate,  hard,  277. 
soft,  277. 


594 


INDEX. 


Palate,  blood  supply  of,  280. 

muscles  of,  278. 
Palatine  arch,  38,  60. 
bone,  59. 
groove,  66. 
Pancreas,  3i8. 

Pancreas  and  liver  in  Avea,  384. 
Panniculus  adiposus,  542. 
Papillae  of  the  tongue,  284. 
Parietal  bone,  47. 

branches  of  posterior  aorta,  403. 
Parotid  gland,  285. 
Par-ovarium,  359. 
Pastern  bone,  large,  80. 
bone,  small,  81. 
joint,  142. 
Patella,  91. 
Pathetic  nerves,  492. 
Pecten,  554. 
Pectoral  arch,  66. 

arch  in  birds,  117. 
limb,  66. 

articulations  of,  136. 
fascia  of,  254. 
Peduncles  of  the  cerebellum,  476. 

cerebrum,  477. 
Pelvic  apertures  87, 
arch,  83. 
cavity,  83. 
limb.  88. 

articulations  of,  143. 
fasciae  of,  255. 
symphpsis,  146. 
Pelvis,  83. 
Penis,  353. 

arteries  and  nerves  of,  366. 
Pericardium,  397. 
Perichondrium,  121. 
Pericranium,  12. 
Perilymph,  530. 
Perineal  fascia.  356. 
Perinaeum,  356, 362. 
Periople,  545. 
Perioplic  ring,  551. 
Periosteum,  11. 
Perissodactyla,  4. 
Peritoneum,  321. 
Petrosal  bone,  50. 

ganglion,  499. 
sinuses,  489. 
Phalanx,  distal,  81. 
median,  81. 
proximal,  80. 
Pharyngeal  muscles,  297. 
Pharynx,  596.. 
Phrenic  centre,  208. 
Physiology  distinguished  from  Anatomy, 

2.  , 

Pia  mater.  469, 471. 
Pineal  gland.  484. 
Pisiform  bone.  77. 
Pituitary  gland,  478. 
Placenta,  557. 
Plantar  aponeurosis,  228. 

strengthening  sheath,  229. 
Pleurae,  337. 

Plexuses.    See  Nebves. 
Pneumatic  bones,  119. 
Pneumogastric  nerve,  500. 
Podophyllous  tissue.  550. 
Pons  Tarini.  478. 
Varolii,  475. 
Portio  dura,  497. 
Portio  mollis.  499. 
Porus  opticus,  533. 
Posterior  aorta.  402. 

bifurcation  of,  409. 
parietal  branches  of,  403. 
visceral  branches  of,  404. 
nares,  39. 
vena  cava,  436. 
Poupart's  ligament,  202. 


Practical  anatomy,  2. 
Preening  in  birds,  656. 
Fremaxilla,  57. 
Premaxillary  symphysis,  5H. 
Prepubian  tendon,  201. 
Prepuce,  355. 
Process,  14. 

basilar.  46.     • 

crista  galli,  54. 

olecranon,  72. 

olivary,  53. 

pyramidal,  82. 
Pronation,  154. 
Prostate  gland,  35i. 

vesicle,  351. 
Proventriculus,  384. 
Proximal,  20. 

phalanx,  80. 
Pterygoid  bone,  60. 
Pterygoidean  fasiculus,  431. 
Pubio-femoral  ligament,  146. 
Pubis,  86. 

Pulmonary  artery,  400- 
Puncta  lachrymalia,  540. 

vasculosa,  479. 
Pupil,  535. 
Pyramidal  process,  82. 

QUADBATO-JUGAX,  BONE,  117. 

Ouadrate  bone,  117. 
Quarters,  545. 

Rachis,  554. 

Rachitis,  8. 

Radio- ulnar  arch,  70 

Radius,  70. 

Rami  of  the  Jaw,  38. 


Receptaculum  chyli.  451, 

In  Carnivora,  462. 
Rectum,  3io. 
Removal  of  the  hoof,  567. 
Renal-portal  system,  463. 
Respiratory  organs,  323. 

in  Aves,  385. 
in  Carnivora,  382. 
in  Omnivora,379. 
in  Ruminants,  374, 
Respiratory  system,  323. 
Restiform  bodies,  474. 
Rete  mirabile,  460. 

mucosum,  641. 
Reticular  cartilage,  122. 
Retina,  535. 
Ribs,  33 

special,  36, 
Ridge,  14. 

mastoid,  46. 
semilunar,  82. 
Rigl^t  auricle,  389. 

ventricle,  391. 
Rings,  abdominal,  203. 
Rodentia,  albinos  in,  5.S3. 

appendicular  skeleton,  116, 
characteristics  of.  5. 
axial  skeleton,  114 
"  Roosting."  mechanism  of,  2r,9. 
Ruminantia,  appendicular  skeleton  of,106. 
bones  of  skull,  9k 
characteristics  of,  4. 
horns  in,  552. 
vertebrae  of,  102. 
visceral  skeleton  of.  105. 

Sacculus  communis,  531. 

proprius,  531. 
Paccus  endoly 'nphaticus,  531. 
Sacral  nerves,  506. 

vertebrae,  31. 
Pacro-iliac  joint,  143. 
Sii'To-lumbar  arliculation,  132. 
Sacro-sciatic  ligament,  144. 


INDEX. 


595 


Sacrnm,  31. 
Saliva,  288. 
Salivary  glands.  285. 
Scala  intermedia,  531. 
tympani,  530. 
vestibuli,  630. 
Scaphoid,  73. 
Scapula,  66. 
Scapus,  554. 

Schneiderian  membrane,  526. 
Sclerotic  coat,  532. 
Scrotum,  347. 
Scutiform  cartilage,  526. 
Sebaceous  glands,  542. 
Sella  turcica,  53, 
Semicircular  canals.  530. 
Semilunar  cartilages,  347. 
ganglion,  520. 
ridge,  82. 
Seminal  fluid,  356. 
Sensation,  organs  of,  525. 
Sensitive  frog,  55(i. 

laminae,  551. 
sole,  551. 
Separate  bones  of  the  skull,  45. 
Beptum  lucidum,  480. 

pectiniforme,  354. 
Serous  membranes,  273. 
Sesamoid  bones,  large,  80. 
small,  83. 
Sesamoidean  ligaments,  141, 
Sharpey,  fibres  of,  10. 
Sheath,  355. 
Shoulder  joint,  136. 
Sinus  pocularis,  351. 
Sinuses,  cavernous,  489. 
ethmoidal,  45. 
frontal,  44. 
lactiferous,  364. 
lateral,  489. 
longitudinal,  489. 
maxillary,  44. 
occipital,  489. 
of  tne  dura  mater,  488. 
of  the  skull,  44. 
petrosal,  489. 
sphenoidal,  45. 
transverse,  489. 
Skeleton,  17. 

appendicular.  65. 
axial,  21. 
division  of,  20. 
in  Birds,  115. 
in  Carnivora,  log- 
in Hog,  105. 
in  Rodentia,  114. 
in  Ruminants,  98. 
Skin,  541. 

in  Carnivora,  553. 
in  Omnivora,  552. 
Skull,  articulations  of,  134. 
cavities  in,  42. 
division  of,  37. 
general  view,  37. 
of  Dog,  109. 
of  Hog,  105. 
of  Ruminant,  98. 
separate  bones  of,  45. 
sinuses  of,  44. 
sutures  of,  134. 
Snout,  379, 
^ole.  546. 
Solidungula,  4. 
Space,  atlo-axoid,  28. 

interdental,  38,  57,  63. 
maxillary,  62. 
Special  anatomy,  l. 

ligaments  of  carpus,  137. 
ligaments  of  tarsus,  150.    . 
ribs,  35. 

vertebral  articulations,  131. 
vertebral  ligaments.  130. 


Speculum  Helmontii,  208. 
Spermatic  cord,  347. 
Spermatozoa,  356. 
Sphenoid  bone,  52. 
Sphenoidal  sinus,  45. 
Spheroidal  epithelium,  271. 
Spinal  accessory  nerve,  502. 
Spinal  cord,  471. 

meninges  of,  468. 
Spine,  14. 
Splanchnology,  270. 

comparative,  365. 
Spleen,  319. 
Splint  bone,  78. 
Squamosal  bone,  49. 
Squamous  epithelium,  270. 
Stapes,  527. 

Sternal  articulations,  134. 
Sternebrae,  35. 
Sternum,  35. 
Stifle  bone,  91. 
joint,  146. 
Stomach,  30i. 

in  Carnivora,  381. 

in  Omnivora,  378. 

in  Rodents,  383, 

in  Ruminants,  366. 
Strangeways  on  a  supernumerary  obliaw'' 

muscle  of  the  eyeball,  575. 
Strengthening  plantar  sheath,  229. 
Striated  muscular  tissue,  156. 
Structure  of  bone,  7. 

minute,  9. 
Sudoriferous  glands,  542. 
Superflcial  fascia,  159. 
Superior  maxilla,  56. 

pyramids,  475. 
Supination,  154. 
Supracondyloid  fossa,  89. 
Suprarenal  capsules,  343. 
Surfaces  of  bones,  14. 
Surgical  anatomy,  2. 
Suspensory  ligament,  141, 
Sutures,  126. 

of  the  skull,  134. 
Symmetry,  bilateral,  19. 
Sympathetic  system  of  nerves,  516. 
Symphysis,  pelvic,  145. 

premaxillary,  58. 
inferior  maxillary,  63. 
Synarthrosis,  126. 
Syudesmology,  120. 
Synovia,  125. 
Synovial  bursas.  125. 

membranes,  124. 
Syrinx,  285. 
System,  hsemal,  3. 

Table  of  muscular  attachments,  256. 
Taenia  semicircuiaris,  482. 
Tapetum  lucidum,  534. 

in  carnivora  658 
Tarsal  cartilages,  539. 
Tarsus,  93. 
Teeth  288. 

'arrangement,  and  kinda«»f,  290. 

canine.  293. 

in  Carnivora.  380. 

in  Rodents,  383. 

incisor,  291. 

molar,  293. 
Temporal  bone,  49. 
fossa,  41. 
Temporary  cartilage,  15. 
Temporo-maxillary  joint,  134. 
Tendons,  158. 
Tendo-Achillis,  248. 
Tendon,  prepubian,  201. 
Tentorium  cerebelli,  470. 
ossiflc,  42.  47. 


Testicle, 


596 


INDiiX. 


Testicle  in  Carnivora,  383. 
Tensor  palati  muscle,  278. 
Third  ventricle,  483. 
Thorax.  33,  336. 
Thoracic  articulations,  132. 

duct,  451. 
Thoracic  duct  in  Omnivora,  461. 
Thyroid  and  Thymus  glands,  335. 
Tibia,  91. 
Tibial  arch,  93. 

Tibio-fibular  articulation,  148. 
Tissue,  adipose,  123. 

cancellated,  10. 

compact,  9. 

connective,  122. 

horn,  548, 

muscular.  155. 

osseous,  9. 

white  fibrous,  122. 

yellow  elastic,  123. 
Tongue,  280. 

muscles  of,  281. 
papillae  of,  284. 
Torcular  Herophili,  489. 
Touch-hairs,  553. 
Trachea,  334. 

Transcendental  anatomy.  1. 
Transverse  sinus  489. 
Trapezium,  75. 
Trapezoid,  75 . 
Trifacial  nerves,  492. 
Trochanter,  14. 
Trochlea,  19. 

True  vertebrae— general  view,  21. 
Tuber  cinereum,  478. 
Tubercle,  14. 
Tuberosity,  14. 
Tubuli  uriniferi,  341, 

seminiferi,  349. 
Tunica  abdominalis,  200. 

albuginea,  349,  358,  553. 

Ruyschiana.  534. 

vaginalis,  348. 

vasculosa,  349. 
Tunics  of  the  eyeball,  532. 
Turbinals.  61.  , 

Turner,  Professor,  on  a  muscle  connected 

with  orbital  periosteum,  577. 
Tusks,  5.  / 

Tympanic  membrane,  526, 
Tympanum,  526. 
Types  in  anatomy.  1. 

Ulna,  71. 

development  of,  72. 103. 
Umbilical  cord,  558. 
Umbilicus,  201. 
Unciform  bone,  76. 
Ungulata,  4. 
Urachus,  558. 
Ureters,  343. 
Urethra,  352. 
Urinary  system.  340. 
Urino-genital  system  in  Aves,  386. 

in  Carnivora,  382. 

in  Omnivora,  379. 

in  Rodentia,  383. 

in  Ruminants,  374, 
Uropygeal  gland,  555. 
Utero-gestation,  656. 
Uterus,  359. 

forms  of,  384. 


Vagina,  361. 
Valve  of  Vieussens,  475. 
Vas  deferens,  350. 
Vater,  eminence  of,  317. 
Veins,  structure  of,  433. 

alveolar,  447. 

angular,  447. 

anterior  auricular,  446. 


Veins,  anterior  cava,  442. 

anterior  mesenteric,  437. 

anterior  radial  445. 

anterior  tibial,  441. 

azygos,  444. 

basilic.  445. 

brachial,  444,  445. 

bronchial.  435. 

buccal,  449. 

cardiac,  435. 

cephalic,  445,  449. 
1  common  iliac,  438. 

coronary,  435,  448. 

coronary  plexus,  440. 

cubital,  44S. 

deep,  of  arm,  445. 

deep,  of  brain,  488. 

deep,  of  posterior  limb,  441. 

deep,  or  interosseous,  of  anterior 
extremity,  444. 

diaphragmatic.  437. 

digital,  440,  444. 

dorsal,  443. 

dorsans  nasi,  447, 

duodenum,  437. 

emergent  veins  of  the  cranium,  489. 

encephalic  sinuses,  488. 

external  iliac,  439,  442. 

external  saphenic,  442. 

external  subcutaneous  of  arm,  446. 

femoral,  442. 

gastric,  437. 

gastro-epiploic,  437. 

gastro-splenic,  437. 

glosso-facial,  447. 

hepatic,  437. 

humeral,  445. 

in  Aves,  463. 

in  Omnivora,  461. 

In  Ruminants,  460. 

inferior  communicating,  449. 

internal  iliac,  442. 

internal  maxillary,  447. 

internal  saphenic,  441. 

internal  subcutaneous  of  arm,  446, 

internal  thoracic,  443. 

interosseous  of  foot,  440. 

jugular,  446. 

jugular,  branches  of,  447. 

jugular  confluent,  446. 

laminal  plexus,  439. 

lateral  coronary  plexus,  440. 

lateral  nasal,  447. 

lesser  azygos,  443. 

lingual,  447, 

lumbar.  438. 

maxillo-muscular,  447. 

metacarpal,  444. 

metatarsal,  440. 

middle  coronary.  440. 

occipital,  447. 

of  the  brain.  488. 

of  the  foot,  439. 

of  the  Frog,  440. 

pancreatic,  437. 

parietal-temporal  (confluent),  489t 

pedal  plexuses  of  ante"rior  limb, 

444. 
phrenic,  437. 
popliteal,  442. 
portal,  437. 

posterior  auricular,  447. 
posterior  mesenteric,  437. 
posterior  radial,  444. 
posterior  tibial,  441. 
posterior  vena  cava,  436. 
pulmonary,  435. 
pyloric,  437. 
renal,  437. 
sa^hena  major,  441. 
saphena  minor.  442. 
satellite,  434. 


mDEX. 


597 


Veins,  sesamoidean  arch,  440. 
solar  plexus,  439. 
spermatic,  437. 
spermatic  plexus,  438. 
spinal,  490. 
spur,  445. 

subcutaneous  thoracic,  445. 
sublingual,  449. 
subsphenoidal  (confluent),  489. 
subzygomatic,  446. 
superior  cerebral,  446. 
superior  cervical,  443. 
superior  and  inferior  coronary,  448, 
superficial  of  arm,  445. 
superficial  of  arm,  445. 
superficial  of  brain,  488. 
superficial  of  posterior  limb,  441. 
superficial  temporal,  446. 
systemic,  435. 
thyroid,  449.- 
ulnar,  445. 
umbilical,  559. 
utero-ovarian,  438.      ^ 
valves  of,  434. 
vena  varicosa,  447. 
vertebral,  443. 
venae  vorticosas  534. 
vetlum  interpositum,  482. 
Ventricles  of  brain,  476. 

of  heart,  389. 

of  larynx,  330. 
Vermiform  process,  475. 
Vertebrae,  cervical,  general  features,  23. 

cervical,  special,  26. 

cervical,  the  two  last,  28, 

coccygeal,  32. 

dorsal,  28. 

false,  general  view.  23. 

in  the  Dog,  ill. 

in  the  Hog  107. 


Vertebrae,  in  Ruminants,  102. 

lumbar,  30. 

sacral,  31, 

true,  general  view,  21. 
Vertebral  column,  21. 
Vertebrata,  3. 

low  forms  of,  4. 
Verumontanum,  353. 
Vesiculae  seminales,  350. 
Vessels  of  bone  tissue,  12. 
Vestibule.  5-29. 
Veterinary  anatomy,  2. 
Vexillum,  554. 

Visceral  branches  of  posterior  aorta, 
skeleton  in  Carnivora,  113. 

in  fiuminantia,  105. 
Vidian  fissure,  52. 
Vitreous  humour,  535. 
Vomer.  61. 
Vulva,  361, 

Wall  of  the  hoof,  545. 
Wattles,  655. 
Web-ffe>t,  555. 
White  fibrous  tissue,  122. 
Wind  galls,  142. 
Withers,  30. 
Wolffian  bodies,  557. 
Wormian  bone,  48. 

xlvbocd  cabtilage,  3s. 

Yellow  elastic  tissue,  128. 

Zonula  of  Zinn,  536. 
Zoology,  1. 
Zootomy,  l. 
Zygomatic  arch,  40.  49. 
process,  68. 


CATALOGUE   OF 

William  R.  Jenkins  Co.'s 

Works  Concerning 

HORSES,  CATTLE,  SHEEP,  SWINE,  Etc. 

1908 


(*)  Designates  New  Books. 

(f)  Designates  Recent  Publications. 


ANDERSON.  "Vice  in  the  Horse"  and  other  papers 
on  Horses  and  Riding.  By  E.  L.  Anderson.  Size, 
6x9,  cioth,  illustrated .1  75 

ARM  STEAD.     "  Tlie  Artistic  Anatomy  of  tlie  Horse." 

A  brief  description  of  the  various  Anatomical  Struc- 
tures which  may  be  distinguished  during  Life  through 
the  Skin.  By  Hugh  W.  Armstead,  M.D.,  F.R.C.S. 
With  illustrations  from  drawings  by  the  author. 
Cloth  oblong,  10  x  12^ 3  75 

BACH,  "How  to  Judge  a  Horse."  A  concise  treatise 
as  to  its  Qualities  and  Soundness ;  Including  Bits  and 
Bitting,  Saddles  and  Saddling,  Stable  Drainage,  Driv- 
ing One  Horse,  a  Pair,  Four-in-hand,  or  Tandem,  etc. 
By  Capt.  F.W.  Bach.     Size,  5x7^,  clo.,  fully  illus.l  00 

BANHAM.  "Tables  of  Veterinary  Posology  and  Tliera. 
peutics,"  with  weights,  measures,  etc.  By  Geo.  A- 
Banham,  F.  R.  G.  V.  S.  New  edition.  Cloth,  size 
4x5  1-2,  192  pages 1  00 

BAUCHER.  "Metliod  of  Horsemanship."  Including 
the  Breaking  and  Training  of  Horses.  By 
F.  Baucher 1  00 

BELL.  (*)"The  Veterinarian's  Call  Book  (Perpetual)." 
By  Roscoe  R.  Bell,  D.V.S.,  editor  of  the  American 
Veterinary  Review.    Completely  revised  1907. 

A  visiting  list,  that  can  be  commenced  at  any  time 
and  used  until  full,  containing  much  useful  informa- 
tion for  the  student  and  the  busy  practitioner. 
Among  contents  are  items  concerning:  Prescription 
writing;  Veterinary  Drugs;  Poisons;  Solubility  of 
Drugs;  Composition  of  Milk,  Bile,  Blood,  Gastric 
Juice,  Urine,  Saliva ;  Respiration ;  Dentition ;  Temp- 
erature, etc.,  etc.  Bound  in  flexible  leather,  with 
flap  and  pocket. ,,...,,,,,, .,,.,,..,....  1  25 


BITTING.    *•  Cadiot's  Exf rcisf s  in  Equine  Surgery." 

See  ''Cadioi." 
BRADLJEY.         *'  Outlines      of     Yeterinary    Anatomy." 

By  O.Charnock  Biadlej-,  Member  of  the  Royal  Col- 
lege of  Veterinary  Surgeons ;  Professor  of  Anatomy 
in  the  New  Veterinary  College,  Edinburgh. 

The  author  presents  the  most  important  facts  of 
veterinary  anatomy  in  as  condensed  a  form  as  possible, 
consistent  with  lucidity.     l2mo. 

Complete  in  three  parts. 

Pakt  I. :      The  Limbs  (cloth) 1  25 

Part  II. :     The  Trunk  (paper) 1  25 

Pakt  III. :    The  Head  and  Neck  (paper) 1  25 

The  Set  complete 3  25 

CADIOT.  "  Exercises  in  Equine  Sur^rery."  By  P.  J. 
Cadiot.  Translated  by  Prof.  A.  W.  Bitting,  D.V.M. 
Edited  by  Prof.  A.  Liautard,  M.D.V.M.  Size,  6  x  OX- 
cloth,  illustrated 2  50 

—  "Roaring'   in   Horses."     Its    Pathology   and    Treatment, 

This  work  represents  the  latest  development  in  oper- 
ative methods  for  the  alleviation  of  roaring.  Each 
step  is  most  clearly  defined  by  excellent  full-page 
illusti'ations.  By  P.  J.  Cadiot,  Professor  at  the 
Veterinary  School,  Alfort.  Translated  by  Thos.  J. 
Watt  Dollar,  M.E.C.V.S.,  etc.  Cloth,  size  5  1-4x71-8, 
77  pages,  illustrated 75 

—  "Studies  in  Clinical  Veterinary  Medicine  and  Surgery." 

By  P.  J.  Cadiot.  Translated,  edited,  and  supplemented 
with  49  new  articles  and  3t  illustrations  by  Jno.  A.  W. 
Dollar,  M.R.C.V.S.     Cloth,  size  7  x  9  3-4,  619  pages, 

94  black  and  white  illustrations 5  25 

—(*)"  A  Treatise  on  Surgical  Therapeutics  of  the  Domestic 
Animals."  By  F.  J.  Cadiot  and  J.  Almy.  Translated 
by  Prof.  A.  Liautard,  M.D.,V.M. 

I.  General  Surgery. — Means  of  restraint  of  animals, 
general  anaesthesia,  local  anocthesia,  surgical  anti- 
sepsis and  asepsis,  hematosis,  cauterization,  firing, 

II.  Diseases  Common  to  all  Tissues.— Inflammation, 
abscess,  gangrene,  ulcers,  fistula,  foreign  bodies, 
traumatic  le.sions,  complications  of  traumatic  les- 
ions, granulations,  cicatrices,  mycosis,  virulent 
diseases,  tumors. 

III.  Diseases  Special  to  all  Tissues  and  Affections  of 
the  Extremities. — Diseases  of  skin  and  cellular  tis- 
sue, of  serous  bursae,  of  muscles,  of  tendons,  of 
tendinous  synovial  sacs,  of  aponeurosis,  of  arteries, 
of  veins,  of  lymphatics,  of  nerves,  of  bones,  of 
articulations. 

Cloth,  size  6x9,  580  pages,  118  illustrations 4  50 

CHAPMAN.  "Manual  of  the  Pathological  Treatment 
of  Lameuess  in  the  Horse,"  treated  solely  by 
mechanical  means.  By  George  T.  Chapman.  Cloth, 
size  6x9,  124  pages  with  portrait , 2  OQ 


CLARKE.  "Chart  of  the  Feet  and  Teeth  of  Fossil 
Horses."  By  W.  H.  Clarke.  Card,  size  9  1-2  x  12. .  25 

—*<  Horses'  Teeth."  Fourth  edition,  re-revised,  with  second 
appendix.     Cloth,  size  5  1-4  x  7  1-2,  322  pp.,  illus.. 2  60 

CLEAVJELAND,        "Pronouncing     Medical     Lexicon." 

Pocket  edition.  By  C  H.  Cleveland,  M.D.  Cloth, 
size  3  1-4x4  1-2,  302  pages 75 

CLEMENT.  *'  Veterinary  Post  Mortem  Examina- 
tions." By  A.  W.  Clement,  V.S.  The  absence  in  the 
English  language  of  any  guide  in  making  autopsies 
upon  the  lower  animals,  Induced  Dr.  Clement  to 
write  this  book,  trusting  that  it  would  prove  of  prac- 
tical value  to  the  profession.  Cloth,  size  5x7  1-2,  64 
pages,  illustrated 75 

COURTENA  F.  (f)  "  Manual  of  the  Practice  of  Veterinary 
Medicine."  By  Edward  Courtenay,  V.  S.  Revised  by 
Frederick  T.  G.  Hobday,  F.R.C.V.8.  Second  edition. 
Cloth,  size  5  1-4x7  1-2,  573  pages    2  75 

COX.       "  Horses  :     In    Accident    and    Disease."       The 

sketches  introduced  embrace  various  attitudes  which 
have  been  observed,  such  as  in  choking  ;  the  disorders 
and  accidents  occurring  to  the  stomach  and  intestines ; 
affection  of  the  brain ;  and  some  special  forms  of  lame- 
Hess,  etc.  By  J.  Roalfe  Cox,  F.R.C.V.S.  Cloth,  size 
6  X  9,  28  full  page  illustrations 1  60 

DALRY3IPLE.  (*)"Veterinary  Obstetrics."  A  compen- 
dium  for  the  use  of  advanced  students  and  Practi- 
tioners. By  W.  H.  Dalrymple,  M.  R.  C.  V.  S., 
principal  of  the  Department  of  Veterinary  Science  in 
the  Louisiana  State  University  and  A.  &  M.  College; 
Veterinarian  to  the  Louisiana  State  Bureau  of 
Agriculture,  and  Agricultural  Experiment  Stations. 
Second  edition  revised.  Cloth,  si-'.e  6x9  1-4,162  pages, 
51  illustrations 2  50 

DALZIEL.  "  Breaking  and  Training  Dogs."  Part  I,  by 
Pathfinder.  Part  II,  by  Hugh  Dalziel.  Cloth, 
illustrated 2  50 

—  "Tlie   Collie."    By  Hugh  Dalziel.    Paper,  illustrated. ...  50 

—  "The  Diseases  of  Dogs."    Causes,  symptoms  and  treatment. 

By  Hugh  Dalziel.  Illustrated.  Paper,  50c.  Cloth,  1  CO 

—  "Diseases  of  Horses."    Paper 50 

—  "  The  Fox  Terrier."    By  Hugh  Dalziel.    Paper,  50 ;  clo.l  00 

—  "The  Greyhound."   Cloth,  illus 1  OO 

—  "  The  St.  Bernard."    Cloth,  lUuitrated ,,,.,.,,,..:[  qQ 


VANA.  "Tables  in  Comparatiye  Phygiology,"  By  Prof. 
C.  L.  Dana,  M.D.     Chart,  17  x  17 26 

DANCE.  "Veterinary  Tablet."  By  A.  A.  Dance.'  Chart, 
17  X  24,  mounted  on  linen,  folded  in  a  cloth  case  for 
the  pocket,  size  3  3-4  x  6  1-2.  Shovps  at  a  glance  the 
eynopsis  of  the  diseases  of  horses,  cattle  and  dogs ; 
with  their  cause,  symptoms  and  cure 75 

DE  BBUIN.  (*)" BoTine  Obstetrics."  By  M.  G.  De  Bruin 
Instructor  of  Obstetrics  at  the  Slate  Veterinary 
School  in  Utrecht.  Translated  by  W.  E.  A.  Wyman, 
formerly  Professor  of  Veterinary  Science  at  Clemson 
A.  &  M.  College,  and  Veterinarian  to  the  South 
Carolina  Experiment  Station.  Cloth,  size  6x9,  382 
77  illustrations 5  00 


Synopsis  of  the  Es»sential  Features  of  tbe  Work 

1.  Authorized  translation. 

2.  The  only  obstetrical  work  which  is  up  to  date. 

3.  Written  by  Europe's  leading  authority  on  the  subject. 

4.  Written  by  a  man  who  has  practiced  the  art  a  lifetime. 

5.  Written  by  a  man  who,  on  account  of  his  eminence  as 
bovine  practitioner  and  teacher  of  obstetrics,  was  selected 
by  Prof.  Dr.  FrOhner  and  Prof.  Dr.  Bayer  (Berlin  and 
Vienna),  to  discuss  bovine  obstetrics  both  practically  and 
scientifically. 

6.  The  only  work  containing  a  thorough  differential  diaK- 
nosis  of  arte  and  post  partmn  diseases. 

7.  The  only  work  doing  justice  to  modern  obstetrical 
surgery  and  therapeutics. 

8.  Written  by  a  man  whose  practical  suggestions  revolu- 
tionized the  teaching  of  veterinary  obstetrics  even  in  the 
great  schools  of  Europe. 

9.  The  only  work  dealing  fully  with  the  now  no  longer 
obscure  contagious  and  infectious  diseases  of  calves. 

10.  Absolutely  original  and  no  compilation. 

11.  The  only  work  dealing  fully  with  the  difficult  problem 
of  teaching  obstetrics  in  the  colleges. 

12.  The  only  work  where  the  practical  part  is  not  over- 
shadowed by  theory. 

...  A  veterinarian,  particularly  if  his  location  brings  him  in 
contact  with  obstetrical  practice,  who  makes  any  pretence  toward 
beinvc  scientific  and  in  possession  of  modern  knowledge  upon  this 
subject,  will  not  be  without  this  excellent  work,  as  it  is  really  a  very 
valuable  treatise.— Pro/.  Roscoc  R.  BcU,  iu  the  American  Veterinary 
Review.         , 

In  translating  into  English  Professor  De  Bruin's  excellent  text- 
book on  Bovine  Obstetrics,  Dr.  Wyman  has  laid  British  and  American 
veterinary  surgeoTis  and  students  under  a  debt  of  gratitude.  The 
works  represents  the  happy  medium  between  the  booklets  which  are 
adapted  for  cramming  purposes  by  the  student,  and  the  ponderofus 
tomes  which,  although  useful  to  the  teacher,  are  not  exactly  suited  to 
the  requirements  of  the  everyday  practitioner  .  .  .  We  can  strongly 
recommend  the  work  to  veterinary  students  and  practitioners.— The 
Journal  uf  Coi)\parative  Pathology  and  Therapeutics. 

DOLLAR.  f*)" Diseases  of  Cattle,  Slieep,  Goats  and 
Swine."  By  G.  Moussu  and  Jno.  A.  W.  Dollar, 
M.Il.C.V.S.  Size  6x9  1-2,  785  pages,  329  illustrations 
in  the  text  and  4  full  page  plates 8  75 

—  (t)'*A.  Hand-book  of  Horse-Shoeing,"  with  Introductory 
chapters  on  the  anatomy  and  physiology  of  the 
hor.se'8  foot.  By  Jno.  A.  W.  Dollar,  M.E.C.V.S., 
with  the  collaboration  of  Albert  Wheatley,  F.E.C.V.S. 
gioth,  size  6x8  1-2,  433  pa^'es,  4C6  illustrations  .  .4  76 


DOLLAK  (continued) 

—  (t)* 'Operative  Tochnuiue."     Volume  1  of  "The  Practice  of 

Veterinary  Surgery."  Cloth,  size  6  3-4  x  10,  264  pages, 
272  illustrations 3  75 

—  *'  General  Suri^ery.*'    Volume  2  of  "The  Practice  of  Veter- 

inavy  Surgery."     In  preparation. 

—  (f)"  Regional  Veterinary  Surgery."     Volume  3  of  "The 

Practice  of  Veterinary"  Surgery."  By  Drs.  Jno.  A. 
W.  Dollar  and  H.  MoUer.  Cloth,  size  6  1-2  x  10  853 
and  xvi  pages,  315  illustrations 6  25 

—  "Catliot's  Clinical  Veterinary  Medicine  and  Surgei'y." 

See  "  Cadiot." 

—  "Cadiot's  Roaring  in  Horses."    See  "  Cadiot." 

DUN.     "Veterinary  Medicines,  their  Actions  and  Uses." 

By  Finlay  Dun,  V.S.,  late  lecturer  on  Materia 
Medica  and  Dietetics  at  the  Edinburgh  Veterinary 
College,  and  Examiner  in  Chemistry  to  the  Eoyal 
College  of  Veterinary  Surgeons.  Edited  by  James 
Macqueen,  F.R.C.V.S.  Tenth  revised  English  edition. 
Cloth,  size  6x9 3  75 

FLEMING.  "  The  Contagious  Diseases  of  Animals."  Their 
influence  on  the  wealth  and  health  of  nations  and  how 
they  are  to  be  combated.  Paper,  size  5x7  1-2, 
30  pages 25 

—  "  Human  and  Animiil  Variolae."    A  Study  in  Comparative 

Pathology.      Paper,  size  5  1-2x8  1-2,  61  pages 25 

— '  "Parasites  and  Parasitic  Diseases  of  the  Domesticated 
Animals."  By  L.  G.  Neumann.  Translated  by 
Dr.  Fleming.     See  "  Neumann." 

—  "Operative  Veterinary  Surgery."     Vol.    I,   by  Dr.  Geo. 

Fleming,  M.R.C.V.S.  This  valuable  work,  one  of  the 
most  practical  treatises  yet  issued  on  the  subject  in 
the  English  language, is  devoted  to  the  common  opera- 
tions of  Veterinary  Surgery ;  and  the  concise  descrip- 
tions and  directions  of  the  text  are  illustrated  with 
numerous  wood  engravings.     Cloth,  size  6x9  1-4,  285 

and  xviii  pages,  343  illustrations 2  75 

(*)Vol.  II,  edited  and  passed  through  the  press  by 
W.  Owen  Williams,  F.R.C.V.S.  Cloth,  size  6x9  1-4, 
430  and  xxxvii  pages,  344  illustrations 3  25 

—  "  Roaring     in     Horses."         By    Dr.     George      Fleming, 

F.R.C.V.S.  Its  history,  nature,  causes,  prevention 
and  treatment.  Cloth,  size  5  1-2x8  3-4,  160  pages,  21 
engravings,  1  colored  plate 1  50 

—  "  Veterinary  Obstetrics."    Including  the  Accidents  and  Dis- 

eases incident  to  Pregnancy,  Parturition,  and  the  Early 
Age  in  Domesticated  Animals.  By  Geo.  Fleming. 
F.R.C.V.S.    Cloth,  size  6x8  3-4,  758  pages,  iUus.6  25 


OOTTHIEL.     n"A    Manual    of    General     Histology. 

By  Wm.  S.  Gottheil,  M.D.,  Professor  of  Pathology  in 
the  American  Veterinary  College,  New  York;  etc.,  etc. 
Histology  is  the  basis  of  the  physician's  art,  aB 
Anatomy  is  the  foundation  of  the  surgeon's  science. 
Only  by  knowing  the  processes  of  life  can  we  under- 
stand the  changes  of  disease  and  the  action  of 
remedies;  as  the  architect  must  know  his  building 
materials,  so  must  the  practitioner  of  medicine  know 
the  intimate  structure  of  the  body.  To  present  this 
knowledge  in  an  accessible  and  simple  form  has 
been  the  author's  task.  Second  edition  revised. 
Cloth,  size  5  1-2  x  8,  152  pages,  68  illustrations. .  .1  00 

GBESSWELL.    "Diseases  and  Disorders  of  the  Horse." 

A  Treatise  on  Equine  Medicine  and  Surgery,  being  a 
contribution  to  the  science  of  comparative  pathology. 
By  Albert,  Jas.  B.  and  Geo.  Gresswell.  Cloth,  size 
5  3-4x8  3  4,  227  pages,  illustrated. 1  75 

—  "  The  Bovine  Prescriber."    For  the  use  of  Veterinarians 

and  Veterinary  Students.  Second  edition,  revised 
and  enlarged,  by  James  B.  and  Albert  Gresswell, 
M.R.C.V.S.     Cloth,  size,  5  X  7  1-2,  102  pages 75 

—  "The  Equine  Hospital  Prescriber."    For  the  use  of  Veter- 

inary Practitioners  and  Students.  Third  edition  re- 
vised and  enlarged,  by  Drs.  James  B.  and  Albert 
Gresswell,  M.R.C.V.S.  Cloth,  size  5  x  7  1-2,  165 
pages 76 

—  Manual  of  "The  Theory  and  Practice  of  Equine  Medicine." 

By  James  B.  Gresswell,  F.R.C.V.S.,  and  Albert 
Gresswell,  M.R.C.V.S.  Second  edition  revised. 
Cloth,  size  5  1-4x7  1-2,  539  pages 2  75 

—  (t)  "Veterinary  Pharmacopseia  and  Manual  of  Comparative 

Therapy."  By  George  and  Charles  Gresswell,  with 
descriptions  and  physiological  actions  of  medicines, 
by  Albert  Gresswell.  Second  edition  revised  and 
enlarged.     Cloth,  6x8  3-4,  457  pages 3  50 

HASSLOCH.  "  A  Compend  of  Veterinary  Materia  Medica 
and  Therapeutics."  By  A.  C.  Hassloch,  V.S., 
Lecturer  on  Materia  Medica  and  Therapeutics,  and 
Professor  of  Veterinary  Dentistry  at  the  New  York 
College  of  Veterinary  Surgeons  and  School  of  Compa- 
rative Medicine,  N.  Y.  Cloth,  size  5  1-4x7  1-2,  225 
pages 1  50 

HEATLEY.  "  The  Stock  Owner's  Guide."  A  handy  Medi- 
cal Treatise  for  every  man  who  owns  an  ox  or  cow. 
By  George  S.  Heatley,  M.R.C.V.S.  Cloth,  size 
5  1-4  X  8,  172  pages 1  26 


HILL.  (I)" The  Diseases  of  the  Cat."  By  J.  Woodroffe 
Hill,  F.R.C.V  S.     Cloth,  size  5  14x7  1-2,  1!!3  pages, 

illustrated 1  25 

Written  from  the  experience  of  many  years'  prac- 
tice and  close  pathological  research  into  the  maladies 
to  which  our  domesticated  feline  friends  are  liable — a 
subject  which  it  must  be  admitted  has  not  found  the 
prominence  in  veterinary  literature  to  which  it  is 
undoubtedly  entitled. 

—  "The   Management   and   Diseases    of  the   Doff"     By  J. 

Woodroffe  Hill,  F.R.C.V.S.  Cloth,  size  5x7  1-2, 
extra  fully  illustrated . 

HINEBAUCH.    "Veteriuary  Dental  Surgery."    By  T.  D. 

Hinebauch,  M.S.V.S.  For  the  use  of  Students,  Prac- 
titioners and  Stockmen.  Cloth,  size  5  1-4  x  8,  256 
pages,  illustrated 2  00 

HO  ARE.  (*)"A  Manual  of  Veterinary  Therapeutics  and 
Pharmacology."  By  E.  Wallis  Hoare.  F.R.C.V.S. 
Cloth,  size  5  1-4x7  1-4,  xxvi  plus  780  pages 4  75 

HOBDAY,  (t)"  The  Castration  of  Cryptorchid  Horses  and 
the    Ovariotomy    of    Troublesome     Mares."     By 

Frederick  T.  G.  Hobday,  F.R.C.V.S.  Cloth,  size 
6  3-4  x  8  3-4,  1C6  pages,  34  illustrations 1  75 

HUNTING,  (f)  The  Art  of  Horse-shoeing.  A  manual 
for  Horseshoers.  By  William  Hunting,  F.R.C.V.S., 
ex-President  of  the  Royal  College  of  Veterinary  Sur- 
geons. One  of  the  most  up-to-date,  concise  books  of 
its  kind  in  the  English  language.  Cloth,  size  6x9  1-4. 
126  pages,  96  illustrations 1  00 

JENKINS.     (*)"  Anatomical  and  Physiological  Model  of 

the  Cow."  Half  life  size.  Composed  of  superposed 
plates,  colored  to  nature,  showing  internal  organs, 
muscles,  skeleton,  etc.,  mounted  on  strong  boards, 
with  explanatory  text.  Size  of  Model  opened, 
10  ft.  X  3  ft.,  closed  3  ft.  x  It  ft 12  00 

—  "Anatomical  and  Physiological   Model    of  the   Horse." 

Half  life  size.     Size  of  Model  38  x  41  in 12  CO 

These  models  may  also  be  obtained  in  smaller 
sizes  together  with  Models  of  the  Dog,  Sheep  and 
Pig. 

JONES.      (*)"The   Surgical   Anatomy    of   the    Horse." 

By  Jno.  T.  Share  Jones,  M.R  C.V.S.  Part  I.  To  be 
completed  in  four  parts.  Each  part — paper,  $4.25 ; 
cloth,  $5.00.  Subscriptions  for  the  four  parts,  pay- 
able in  advance,  paper,  $15.00 ;  cloth,  $17.50. 


KOBEBT.  "Practical  Toxicology  for  Physicians  and 
Students  "  By  Professor  Dr.  Rudolph  Robert. 
Medical  Director  of  Dr.  Brehmer's  Sanitarium  for 
Pulmonary  Diseases  at  Goerbersderf  in  Silesia  (Prus- 
sia), late  Director  of  the  Pharmacological  Institute, 
Dorpat,  Kussia.  Translated  and  edited  by  L.  H. 
Friedburg,  Ph.D.  Authorized  Edition.  Practical 
knowledge  by  means  of  tables  which  occupy  little 
space,  but  show  at  a  glance  similarities  and  differ- 
ences between  poisons  of  the  same  group.  Also  rules 
for  the  Spelling  and  Pronunciation  of  Chemical  Terms, 
as  adopted  by  the  American  Association  for  the  Ad- 
vancement of  Science.     Cloth,  6  1-2  x  10,  201  pp.. 2  60 

KOCH.  "JEtiology  of  Tuberculosis."  By  Dr.  E.  Koch. 
Translated  by  T.  Saure.  Cioth,  size  6x9  1-4,  97 
pages 1  00 

LAMBEBT.       "The      t}erm     Theory       of      Disease." 

Bearing  upon  the  health  and  welfare  of  man  and  the 
domesticated  animals.  By  James  Lambert,  F.R.C.V.S. 
Paper,  size  5  1-4x8  1-4,  26  pages,  illustrated 25 

ItAW.  "Farmers'  Teterinary  Adriser."  A  Guide  to  the 
Prevention  and  Treatment  of  Disease  in  Domestic 
Animals.  By  Prof.  James  Law.  Cloth,  size 
5  1-4x7  1-2,  illustrated 3  00 

LIAUTABD,  (t)" Animal  Castration."  A  concise  and 
practical  Treatise  on  the  Castration  of  the  Domestic 
Animals.  The  only  work  on  the  subject  in  the 
English  language.  By  Alexander  Liautard,  M.D.,V.S. 
Having  a  fine  portrait  of  the  author.  Tenth  edition 
revised  and  enlarged.     Cloth,  size  5  1-4x7  1-2,  165 

pages,  45  illustrations 2  00 

.  .  .  The  most  complete  and  comprehensive  work  on  the 
subject  in  English  veterinary  literature.— American  Agri- 
culturist. 

—  **Cadiot's  Exercises  in  Equine  Surgery."     Translated  by 

Prof.  Bitting  and  edited  by  Dr.  Liautard. 
See  "  Cadiot." 

—  "A  Treatise  on  Surgical  Therapeutics  of  the  Domestic 

Animals."  By  Prof.  Dr.  P.  J.  Cadiot  and  J.  Almy, 
Translated  by  Prof.  Liautard.     See  "  Cadiot." 

—  "  How  to  Tell  the   Age   of  the  Domestic  Animal."    By 

Dr.  A.  Liautard,  M.D.,  V.S.  Standard  work  upon 
this  subject,  concise,  helpful  and  containing  many 
illustrations.  Cloth,  size  5x7  1-2,  35  pages,  42 
illustrations 50 

~  "Lameness  of  Horses  and  Diseases  of  the  Locomotory 
Apparatus."  By  A.  Liautard,  M.D.,V.S.  This  work 
is  the  result  of  Dr.  Liautard's  many  years  of  experi- 
ence.   Cloth,  size  5  1-4x7  1-2,  314  pages 2  63 


LIAUTARD  (continued). 

—  (*)" Manual  of  Operative  Veterinary  Surgery."     By   A. 

Liautard,  M.D.,  V.M.  Engaged  for  years  in  ttiework 
of  teaching  this  special  department  of  veterinary 
medicine,  and  having  abundant  opportunities  of 
realizing  the  difllculties  which  the  student  who 
earnestly  strives  to  perfect  himself  in  his  calling  is 
obliged  to  encounter,  the  author  formed  the  deter- 
mination to  facilitate  his  acquisition  of  knowledge, 
and  began  the  accumulation  of  material  by  the  com- 
pilation of  data  and  arrangement  of  memorandum, 
with  the  recorded  notes  of  his  own  experience,  the 
fruit  of  a  long  and  extended  practice  and  a  careful 
study  of  the  various  authorities  who  have  illustrated 
and  organized  veterinary  literature.  Revised  edition, 
with  complete  index.  Cloth,  size  6  1-4  x  9,  xxx  and  803 
pages,  5G3  illustrations 5  00 

—  **Pellerm's    Median   Neurotomy    in    the   Treatment   of 

Chronic  Tendinitis  and  Periostosis  of  the  Fetlock." 

Translated  by  Dr.  A.  Liautard.     See  "  Pellerin." 

—  "Vade  Mecum   of  Equine   Anatomy."     By  A.  Liautard, 

M.D.V.S.  For  the  use  of  advanced  students  and 
veterinary  surgeons.  Third  edition.  Cloth,  size 
5x7  1-2,  30  pages  and  10  full  page  illustrations  of 
the  arteries . 2  00 

—  Zundel's  "  The  Horse's  Foot  and  Its  Diseases." 

See  "  Zundel." 

LONG.  "  Bool£  of  the  Pig."  Its  selection,  Breeding, 
Feeding  andManagement.    Cloth 4.00 

LOWE.        (t)"  Breeding     Raceliorses      by     the     Figure 

System."  Compiled  by  the  late  C.  Bruce  Lowe. 
Edited  by  William  Allison,  "  The  Special  Commis- 
sioner," London  Sportsman,  Hon.  Secretary  Sporting 
League,  and  Manager  of  the  International  Horse 
Agency  and  Exchange.  With  numerous  fine  illustra- 
tions of  celebrated  horses.  Cloth,  size  8  x  10,  262 
pages • 7  50 

LUDLOW.  "Science  in  the  Stable";  or  How  a  Horse 
can  be  Kept  in  Perfect  Health  and  be  Used  Without 
Shoes,  in  Harness  or  under  the  Saddle.  With  the 
Reason  Why,  Second  Edition.  By  Jacob  R.  Ludlow, 
M.D.  Late  Staff  Surgeon,  U.  S.  Army.  Paper,  size 
4  1-2x  5  3-4,  166  pages 50 

LUPTON.  "Horses:  Sound  and  Unsound,"  with 
Law  relating  to  Sales  and  Warranty.  By  J.  Irvine 
Lupton.  F.R.C.V.S.  Cloth,  size  6  3-4  x  7  1-2,  217 
3  illustrations 1  25 


M'FADTEAN.  (f)  "  Anatomy  of  the  Horse."  Second 
edition  completely  revised.  A  Dissection  Guide. 
By  John  M'Fadyean,  M.B.,  B.Sc,  F.R.S.E.      Cloth, 

size  6  X  8  3  4,  388  pa^es,  illustrated 5  tu 

This  book  is  intended  for  Veterinary  students,  and 
offers  to  them  in  its  48  full-page  colored  plates, 
54  illustrations  and  excellent  text,  a  valuable  and 
practical  aid  in  the  study  of  Veterinary  Anatomy, 
especially  in  the  dissecting  room. 

—  **  Comparatiye  Anatomy  of  the   Domesticated  Animals." 
By  J.  M'Fadyean.     Profusely  illustrated,  and  to  be 
issued  in  two  parts. 
Part  I— Osteology,   ready.      Size  5  1-2x8  1-2,  166 

pages,  132  illustratione.     Paper,  2  50;  cloth 2  75 

(Part  II  in  preparation.) 

MAGNEB.  "Standard  Horse  and  Stock  Book."  By 
D.  Magner.  Comprising  over  1,000  pages,  illustrated 
with  175G  engravings.     Leather  binding.   6  10 

MILLS.  "How  to  Keep  a  Dog  in  the  City."  By 
Wesley  Mills,  M.D.,  D.V.S.  It  tells  how  to  choose, 
manage,  house,  feed,  educate  the  pup,  how  to  keep  him 
clean  and  teach  him  cleanliness.  Paper,  size  5x7  1-2, 
40  pages 25 

MOHLER.  "Handbook  of  Meat  Inspection."  By  Robert 
Ostertag,  M.D.  Translated  by  Eai-ley  Vernon 
Wilcox,  A.M.,  Ph.D.  With  an  introduction  by 
John  E.  Mohler,  V.M.D.,  A  M.     See  "  Ostertag" 

MOLLER  —  DOLLAR.  (f)  "Regional  Veterinary 
Surgery."     See '^  Dollar." 

MOSSELMAN.LIENAUX.  "Manual  of  Veterinary 
Microbiology."  By  Professors  Mosselman  and 
Lienaux,  Nat.  Veterinary  College,  Cureghem,  Belgium. 
Translated  and  edited  by  R.  R.  Dinwiddle,  Professor 
of  Veterinary  Science,  College  of  Agriculture,  Arkansas 
State  University.  Cloth,  size  5  1  2  x  8,  342  pages, 
illustrated 2  00 

MOUSSV.  n"  Diseases  of  Cattle,  Sheep,  Goats  and 
Swine."     See  "  Dollar." 

NEUMANN.  (*)"A  Treatise  on  Parasites  and  Parasitic 
Diseases  of  the  Domesticated  Animals."  A  work 
to  which  the  students  of  human  or  veterinary  medi- 
cine, the  sanitarian,  agriculturist  or  breeder  or  rearer 
of  animals,  may  refer  for  full  information  regarding 
the  external  and  internal  Parasites— vegetable  and 
animal — which  attack  various  species  of  Domestic 
Animals.  A  Treatise  by  L.  G.  Neumann,  Professor 
at  the  National  Veterinary  School  of  Toulouse. 
Translated  and  edited  by  Geo.  Fleming,  C.B.,  LL.D.. 
F.R  C.V.S.  Second  edition,  revised  and  edited  by 
James  Macqueen,  F.R.C.V.S.,  Professor  at  the  Royal 
Veterinary  College,  London.  Cloth,  size  6  3-4  x  in, 
xvi  +  698  pages,  365  illuatratioaa 6  76 


NOCAItiy.  *'  The  Animal  Tuberculoses,  and  their  Relation 
to  Human  Tuberculosis."  By  Ed.  Nocard,  Prof,  of  the 
Alfort  Veterinary  College.  Translated  by  H.  Scurfield, 
M.D.  Ed.,Ph.  Camb.  Cloth,  5  x7  1-2, 143  pages.,!  00 
Perhaps  the  chief  interest  to  doctors  of  human 
medicine  in  Professor  Nocard's  book  lies  in  the 
demonstration  of  the  small  part  played  by  heredity, 
and  the  great  part  played  by  contagion  in  the  propa- 
gation of  bovine  tuberculosis. 

NUNN.  (*)"■  Veterinary  Toxicology."  By  Joshua  A.  Nunn, 
F.R.C.V.S.  The  study  of  toxicology  is  intimately 
blended  with  other  biological  sciences,  particularly 
physiology  and  chemistry,  both  of  which  it  on  many 
occasions  overlaps.  A  carefully  arranged  and  com- 
plete index  is  given  In  the  front  of  the  volume. 
Cloth,  size  6x83-4,  vii  +  191  pages 1  75 

OSTEBTAG.    C)  "  Handbook  of  Meat  Inspection."      By 

Robert  Ostertag,  M.D.  Authorized  Translation  by 
Earley  Vernon  Wilcox,  A.M.,  Ph.D.  With  an  intro- 
duction by  John  E,.  Mohler,  V.M.D.,  A.M.  The  work 
is  exhaustive  and  authorative  and  has  at  once  become 
the  standard  authority  upon  the  subject  Second 
edition,  revised.  Cloth,  size  6  3-4x9  3-4,  920  pages, 
260  illustrations  and  1  colored  plate 7  50 

PALLIN.    (*)  "  A  Treatise  on  Epizootic  Lymphangitis."  By 

Capt.  W.  A.  Pallin,  F.R.C.V.S.  In  this  work  the 
author  has  endeavored  to  combine  his  own  experience 
with  that  of  other  writers  and  so  attempts  to  give  a 
clear  and  complete  account  of  a  subject  about  which 
there  is  little  at  present  in  English  veterinary  litera- 
ture. Cloth,  size  5  3-4x8  1-2,  90  pages,  with  17  fine 
full  page  illustrations 1  25 

PEOLEB.  "  Goat  Keeping  for  Amateurs."  Paper,  5x7i, 
77  pages,  illustrated 50 

PELLEBIN.  "Median  Neurotomy  in  the  Treatment 
of  Chronic  Tendinitis  and  Periostosls  of  the  Fetlock." 

By  C.  Pellerin,  late  repetitor  of  Clinic  and  Surgery  to 
the  Alfort  Veterinary  School.  Translated,  with  Addi- 
tional Facts  Relating  to  It,  by  Prof.  A.  Liautard,  M.D., 
V.M.  Having  rendered  good  results  when  performed 
by  himself,  the  author  believes  the  operation,  which 
coQsists  in  dividing  the  cubito-plantar  nerve  and  in 
excising  a  portion  of  the  peripherical  end,  the  means 
of  improving  the  conditions,  and  consequently  the 
values  of  many  apparently  doomed  animals.  Agricul- 
ture  in  particular  will  be  benefited. 

The  work  is  divided  into  two  parts.  The  first  covers 
the  study  of  Median  Neurotomy  itself ;  the  second, 
the  exact  relations  of  the  facts  as  observed  by  the 
author.    Boards,  6x9  1-2,  61  pages,  illustrated . .  1  00 


PETERS.  "  A  Tuberculous  Herd— Test  nith  Tuber- 
culin." By  Austin  Peters,  M.  R.  C.  V.  S.,  Chief 
Inspector  of  Cattle  for  the  New  York  State  Board  of 
Health  during  the  winter  of  1892-93.     Pamphlet. . .  .25 

REYNOLDS.  "An  Essay  on  the  Breeding  and  Manage- 
ment of  Draught  Horses."  By  R.  S.  Reynolds, 
M.R.C.V.S.     Cloth,  size  5  1-2x8  3-4,  104  pages.  .1  4u 

ROBERGE.  "  The  Foot  of  the  Horse,"  or  Lameness 
and  all  Disea.ses  of  the  Feet  traced  to  an  Unbalanced 
Foot  Bone,  prevented  or  cured  by  balancing  the  foot. 
By  David  Roberge.  Cloth,  size  G  x  9  1-4,  308  pages, 
illustrated 5  00 

I^ESSIONS.  (*)"  Cattle  Tuberculosis,"  a  Practical  Guide  to 
the  Agriculturist  and  Inspector.  By  Harold  Sessions, 
F.R,C.V.S.,  etc.     Second  edition.     Size  5x7  1-4,  vi  + 

120  pages 1  00 

The  subject  can  be  understood  by  those  who  have 
to  deal  particularly  with  it,  yet  who,  perhaps,  have 
not  had  the  necessarj'  training  to  appreciate  technical 
phraseologj'. 

SEWELL.  "The  Examination  of  Horses  as  to  Sound- 
ness and  Selection  as  to  Purchase."  By  Edward 
Sewell,  M.R.C.V.S.     Paper,  size  51-2x8  1-2,  86  pages, 

illastrated  with  8  plates  in  color 1  50 

It  is  a  great  advantage  to  the  business  man  to 

know  something  of  the  elements  of  law,  and  nobody 
ought  either  to  buy  or  own  a  horse  who  does  not  know 
something  about  the  animal.  That  something  this  book 
gives,  and  gives  in  a  thoroughly  excellent  way 

SMITH.  (*)  *♦  A  Manual  of  Yeterinary  Physiology."  By 
Vet.  Capt.  F.  Smith,  C.M.S.,  M.R.C.V.S..  Examiner  in 
Physiology,  Royal  College  of  Veterinary  Surgeons, 
author  of  "A  Manual  of  Veterinary  Hygiene."  A 
completely  revised  and  enlarged  edition  just  pub- 
lished.    Cloth,  6x8  3-4,  720  pp,  102  illust'ns 4  25 

The  whole  book  lias  been  carefully  revised  and 
brought  up  to  date.  All  the  important  advances  of  tlie 
last  few  years  have  been  embodied.  The  chapter  on 
the  nervous  system  has  been  specially  revised  by  Prof. 
Sherrington,  wliose  remarkable  work  on  the  "spinal 
dog"  has  been  introduced.  A  special  point  is  made 
of  the  bearing  of  physiology  on  pathology,  and  the 
utilization  of  physiology  to  the  better  understanding  of 
every-day  practice.  The  book  is  written  by  a  veterin- 
ary surgeon  for  veterinary  practitioners  and  students, 
and  is  the  only  work  in  the  English  language  which 
can  claim  to  be  purely  veterinary. 

—  (*)*^Manual  of  Yeterinary  Hygiene."  Third  edition  revised. 
Cloth,  size  5  1-4x7  1-2,  xx  +  1036  pages,  with  255 

illustrations 4  7ft 

Recognizing  the  rapid  advance  and  extended  field 
of  the  subject  since  the  previous  issue,  the  author 
has  entirely  re-written  the  work  and  enlarged  its 
scope,  whi«h  is  brought  thoroughly  up  to  date.  Con- 
tains over  600  more  pages  than  the  seoond  edition. 


STRANGEWAT.  (t)"Teteriiiary  Anatomy-w"  Edited  by 
I.  Vaughan,  F.L.S.,  M.R.C.V.S.  New  edition  revised. 
Cloth,  size  6  1-4x9  1-2,  625  pages,  224  illus 5  00 

SUSSDORF.    " Six  Large  Colored  Wall  Diagrams."    By 

Prof.  Sussdorf,  M.D.  (of  Gottingeii).  Text  translated 
by  Prof.  W.  Owen  Williams,  of  the  New  "Veterinary 
College,  Edinburgh.     Size,  44  inches  by  30  inches. 

1.— Horse.  4.— Ox. 

2.— Mare.  5.— Boar  and  Sow. 

3.— Cow.                       6.— Dog  and  Bitch. 
The  above  are  printed  in  eight  or  nine  colors. 
Showing  the   position   of   the   viscera  in  the  large 
cavities  of  the  body. 
Price,  unmounted 1  75  each 

•'      mounted  on  linen,  with  roller... 3  50    " 

VAN  MATEB,  <' A  Text  Book  of  Veterinary  Oph- 
tlialmology."  By  George  G.  Van  Mater,  M.D., 
D.V.S.,  Professor  of  Ophthalmology  in  the  American 
Veterinary  College;  Oculist  and  Auristto  St.  Martha's 
Sanitarium  and  Dispensary ;  Consulting  Eye  and  Ear 
Surgeon  to  the  Twenty-sixth  Ward  Dispensary ;  Eye 
and  Ear  Surgeon,  Brooklyn  Eastern  District  Dispen- 
sary, etc.  Illustrated  by  one  chromo  lithograph  plate 
and  71  engravings.  Cloth,  6x9  1-4,  151  pages.. .3  00 
.  .  .  We  Intend  to  adopt  this  valuable  work  as  a  text 
book.— B.  J.  Creely,  D.V.S.,  Dean  of  the  San  Francisco 
Veterinary  College. 

VETERINARY     DIAGRAMS      in     Tabular      Form. 

Size,  28^  in.  x  22  inches.    Price  per  set  of  five 4  00 

Mounted  and  folded  in  case 7  «0 

Mounted  on  roller  and  varnished 10  00 

No.  1.  'The  External  Form  and  Elementary  Ana- 
tomy of  the  Horse."  Eight  colored  illustrations — 
1.  External  regions ;  2.  Skeleton ;  3.  Muscles  (Superior 
Layer) ;  4.  Muscles  (Deep  Layer) ;  5.  Respiratory  Ap- 
paratus ;  6.  Digestive  Apparatus ;  7.  Circulatory  Ap- 
paratus ;  8.  Nerve  Apparatus ;  with  description 1  25 

Mounted  on  roller  and  varnished 2  25 

No.  2.  "The  Age  of  Domestic  Animals."  Forty-two 
figures  illustrating  the  structure  of  the  teeth,  indicat- 
ing the  Age  of  the  Horse,  Ox,  Sheep,  and  Dog,  with 

full  description 75 

Mounted  on  roller  and  varnished 2  00 

No.  3.    "  The  Unsoundness  and  Defects  of  the  Horse." 

Fifty  figures  illustrating— 1.  The  Defects  of  Confor- 
mation ;  2.  Defects  of  Position ;  3.  Infirmities  or  Signs 
of  Disease ;  4.  Unsoundnesses ;  5.  Defects  of  the  Foot ; 

with  full  description 75 

Mounted  on  roller  and  varnished 2  00 


VETERINARY  DIAGRAMS  (continued). 

No.  4.    "The  Shoeing  of  the  Horse,  Mule  and  Ox." 

Fifty  figures  descriptive  i>f  the  Anatomy  and  Physio- 
logy of  the  Foot  and  of  Horse-shoeing 75 

Mounted  on  roller  and  varnished 2  00 

No.  5.  ''The  Elementary  Anatomy,  Points,  and  But- 
cher's Joints  of  the  Ox."  Ten  colored  illustrations 
—1.  Skeleton ;  2.  Nervous  System ;  3.  Digestive 
System  (Right  Side) ;  4.  Respiratory  System  ;  6,  Points 
of  a  Fat  Ox ;  6.  Muscular  System ;  7.  Vascular  System ; 
8.  Digestive  System  (Left  Side) ;  9.  Butcher's  Sections 
of  a  Calf ;  10.  Butcher's  Sections  of  an  Ox ;  with  full 

description 1  25 

Mounted  on  roller  and  varnished 2  25 


WALLET.    "  A  Practical  Guide  to  Meat  Inspection,"    By 

Thomas  Walley,  M.R.C.V.S.,  late  principal  of  the 
Edinburgh  Royal  (Dick)  Veterinary  College;  Pro- 
fessor of  Veterinary  Medicine  and  Surgery,  etc. 
Fourth  Edition,  thoroughly  revised  and  enlarged 
by  Stewart  Stockman,  M.R.C.V.S.,  Professor  of 
Pathology,  Lecturer  on  Hygiene  and  Meat  Inspection 
at  Dick  Veterinary  College,  Edinburgh.  Cloth,  size 
5  1-2x8  1-4,  with  45  colored  illus.,  295  pages 3  00 

An  experience  of  over  30  years  in  his  profession 
and  a  long  official  connection  (some  sixteen  years) 
with  Edinburgh  Abattoirs  have  enabled  the  author  to 
gather  a  large  store  of  information  on  the  subject, 
which  he  has  embodied  in  his  book. 

While  Dr.  Stockman  is  indeed  indebted  to  the 
old  for  much  useful  information,  this  up-to- 
date  work  will  hardly  be  recognized  as  the  old 
'*  Walley 's  Meat  Inspection." 


WILCOX.    (*)''  Handbook  of  Meat  Inspection."     By  Robert 
Ostertag,  M.D.     See  "  Ostertag." 


WILLIAMS.  "Principles  and  Practice  of  Veterinary 
Medicine."  Author's  edition,  entirely  revised  and 
illustrated  with  numerous  plain  and  colored  plates. 
Bv  W.  Williams,  M.R.O.V.S.  Cloth,  size  5  3-4x8  3-4, 
865  pages 7  50 


'*  Principles    and    Practice    of    Veterinary     Surgery." 

Author's  edition,  entirely  revised  and  illustrated 
with  numerous  plain  and  colored  plates.  By  W. 
Williams,  M.R.O.V.S.  Cloth,  size  6  1-2x9  1-4,  756 
pages .7  50 


THE  MOST  COMPLETE,  PROGRESSIVE  AND 
SCIENTIFIC  BOOK  ON  THE  SUBJECT  IN 
THE  ENGLISH  LANGUAGE 

(•)  WINSLOW,    "Veterinary  Materia  Medica  and  Therapeu- 
tics."    By  Kenelm  VVinslow,  B.A.S.,  M.D.V.,  M.D., 

(Harv.) ;  formerly  Assistant  Professor  of  Therapeutics 
in  tlie  .Veterinary  Sciiool  of  Harvard  University ; 
Fellow  of  tiie  Massachusetts  Medical  Society  ;  Surgeon 
to  the  Newton  Hospital,  etc. 

Fifth  Edition,  Revised  and  Enlarged 

Cloth,  size  6  1-4x9  1-4,  x  +  804  pages 6  00 

In  accordance  with  the  hitherto  expressed  desire  of  the  author  and 
publishers  to  keep  this  work  at  its  highest  point  of  efficiency,  it  has 
been  deemed  incumbent  upon  them  to  again  present  a  new  and  revised 
edition— the  fourth  edition  of  1906  being  exhausted. 

In  the  present  revision  the  most  notable  feature  is  the  substitution 
of  a  section  on  Condensed  Treatment  of  Diseases  of  the  Domestic 
Animals  for  the  Index  of  Diseases  and  Remedial  Measures,  at  the  end 
of  the  book.  In  the  preparation  of  this  matter,  very  considerable  time 
and  pains  have  been  taken  to  render  this  section  a  reflection  and  epi- 
tome of  all  that  is  most  modern  and  progressive  in  veterinary  thera- 
peutics. 

Special  indications  for  treatment,  including  drugs  and  therapeutic 
agents  other  than  drugs,  in  the  different  phases  and  stages  of  all  the 
important  diseases  of  the  domestic  animals  are  to  be  found.  These  dis- 
eases embrace  not  only  medical  and  surgical  disorders,  but  those  of  the 
EYE,  SKIN  and  EAR.  If  the  attempt  has  been  in  any  degree  successful, 
this  new  edition  to  the  book  should  prove  one  of  its  most  valuable 
features  both  to  practitioners  and  students. 

Moi'eover,  many  changes  have  been  made  in  the  text  in  consonance 
with  recent  advances  in  our  knowledge  of  the  action  of  drugs. 

—  (*)  "  The  Production  and  Handling-  of  Clean  Milk."    A 

complete,  plain,  practical  and  authoritative  guide  to 
the  production  and  distribution  of  clean  milk  for 
farmers,  health  officers,  milk  inspectors,  students  of 
agriculture  and  dairying,  country  gentlemen,  physi- 
cians and  others  interested  in  matters  pertaining  to 
dairying  and  hygiene.  The  book  also  contains  a 
general  outline  of  a  scheme  for  the  control,  supervi- 
sion and  inspection  of  a  city  milk  supply.  Cloth, 
6  3-4  X  9  3-4,  xii  plus  207  pp.  many  illustrations,  in- 
cluding 1  colored  and  15  full  page  plates 2  50 

WYMA.N.    (*)"BoTine  Obstetrics."     By  M.  G.  De  Bruin. 
Translated  by    W.  E.  A.  Wyman,  M.D.V.,V.S. 
See  also  "  De  Bruin." 

—  (*)" Catechism  of  tlie  Principles  of  Veterinary  Surgery." 

Bv  W.  E.  A.  Wyman,  M.D.V.,V.S.  Cloth,  size  6x9, 
321  pages 3  50 

Concerning  ibis  ne>v  work  attention  is  called  to  the 
follo^viui^  points : 

1.— It  discusses  the  subject  upon  the  basis  of  veterinary  investigations. 

2.— It  does  away  with  works  on  human  pathology,  histology,  etc. 

3.— It  explains  each  question  thoroughly  both  from  a  scientific  as  well 

as  a  practical  point  of  view. 
4.— It  is  writen  by  one  knowing  the  needs  of  the  student. 


WYMAN  (Continued) 

5.— It  deals  exhaustively  with  a  chapter  on  tumors,  heretofore  utterly 

neglected  in  veterinary  pathology. 
6.— The  only  work  in  English  specializing  the  subject. 
7.— The  only  work  thoroughly  taking  into  consideration  American  as 

well  as  European  investigations. 
8.— Offering  practical  hints  which  have  not  appeared  in  print,  the 

result  of  large  city  and  country  practice. 

—  (t/'  The   Clinical  Diagnosis  of  Lameness  in  tlie  Horse." 

By  W.  E.  A.  Wyman,  D.V.S.,  formerly  Professor  of 
Veterinary  Science,  Clemson  A.  &  M,  College,  and 
Veterinarian  to  the  South  Carolina  Experiment 
Station.    Cloth,  size  6x9  1-2,  182  pp.,  32  illus. . .  .2  50 


(t)"Tibio-peroneal  Neurectomy  for  the  Relief  of  Spavin 

Lameness."    By  W.  E.  A.  Wyman,  M.D.V.,  V.S. 

Boards,  size  6  s  9,  30  pages,  illustrated....' 50 

Anyone  wanting  to  perform  this  operation  should  procure 
this  little  treatise ;  he  will  tind  it  of  considerable  help.— TTie 
Veterinary  Journal. 


ZUILL.       "Typhoid    Fever;     or     Contagions     Inflnenia 
in  the  Horse."     By  Prof.  W.  L.  Zuill,  M.D.,D.V.8. 

Pamphlet,  size  6x9  1-4,  29  pages 25 


ZUNDEL.      "The   Horse's   Foot   and   Its   Diseases."    By 

A.  Zundei,  Principal  Veterinarian  of  Alsace  Lorraine. 
Translated  by  Dr.  A.  Liautard,  V.S.  Cloth,  size 
5x7  3-4,  248  pages,  illustrated 2  00 


Any  booh  sent  prepaid  for  the  price 

WILLIAM  R.  JENKINS  CO. 

851  and  853  Sixth  Avenue,  NEW  YORK. 


